A public spending watchdog is investigating claims that the use of premium-rate phone lines by government departments amounts to a "telephone tax".
The National Audit Office expects to deliver its verdict in July, head Amyas Morse told campaigning MP John Healey.
The Labour former minister led calls for a probe after exposing the extent of the use of such numbers. His research found the high-cost lines account for 61% of all telephone lines at 16 government departments and agencies.
Calls to 084- numbers cost up to 41p per minute and the Department for Transport earned £2.5 million from calls in two years.
The Home Office topped the list, with 96% of its lines being high cost: 22 out of 23 lines.
The Department for Work and Pensions was singled out for criticism given the number of low-income users likely to use its phone lines.
Services charging 0845 rates include sections dealing with disability living allowance, carers allowance, job centres and the social fund (can provide help for people on low incomes who are facing emergency expenses), as well as at the Pension Service, Insolvency Service, Rural Payments Agency and the Skills Funding Agency (houses the National Apprenticeship Service and is tasked with increasing apprenticeships).
Work and Pensions Secretary Iain Duncan Smith has since confirmed that new benefit helplines, for personal independence payment and universal credit, will also use 0845.
The HMRC also pocketed £4.7 million worth of free services offered by Cable & Wireless in exchange for 400 million minutes of calls to 0845 numbers.
A Driver and Vehicle Licensing Agency spokesman said: "All the DVLA's phone lines for services to motorists are either free or charged at the local rate. Premium rate lines are only in place in response to requests from the motoring industry and any revenue raised is used to offset the cost of providing this service."
10 of the biggest consumer rip-offs
Government phone lines investigated
Using a mobile phone to make and receive calls, send texts and browse the web while abroad can be extremely costly – especially if you are travelling outside the European Union (EU), where calls can cost up to 10 times as much as at home.
To avoid high charges, Carphone Warehouse suggests tourists ensure a data cap is in place, use applications to check data usage, turn off 'data roaming', avoid data-intensive applications such as Google Maps and YouTube and use wi-fi spots to update social networking sites.
Payment Protection Insurance (PPI) is supposed to help people to continue meeting their loan, mortgage or credit card repayments if they fall ill or lose their jobs. However, policies are often over-priced, riddled with exclusions and sold to people who could not make a claim if they needed to.
At one point, sale of this cover - which was often included automatically in loan repayments - was estimated to boost the banks' profits by up to £5 billion a year.
Now, though, consumers who were mis-sold PPI can fight back by complaining to the bank or lender concerned and taking their case to the Financial Ombudsman Service (08000 234567) should the response prove unsatisfactory.
It could be you, but let's face it, it probably won't be. In fact, buying a ticket for the Lotto only gives you a 1 in 13.9 million chance of winning the jackpot.
With odds like that, you would almost certainly be better off hanging on to your cash and saving it in a high-interest account.
No-frills airlines such as EasyJet may promote rock-bottom prices on their websites. But the overall fare you pay can be surprisingly high once extras such as luggage and credit card payment fees have been added - a process known as drip pricing.
Taking one piece of hold baggage on a return EasyJet flight, for example, adds close to £20 to the cost of your flight, while paying by credit card increases the price by a further £10.
It may therefore be worth comparing the total cost with that of a flight with a standard airline such as British Airways.
Cash advances, which include cash withdrawals, are generally charged at a much higher rate of interest than standard purchases.
While the average credit card interest rate is around 17%, a typical cash withdrawal of £500, for example, is charged at more than 26%.
What's more, as the interest accrues from the date of the transaction, rather than the next payment date, costs will mount up even if you clear your balance in full with your next payment.
Supermarkets such as Tesco and Asda often run promotions under which you can, for example, get three products for the price of two.
However, it is only worth taking advantage of these deals if you will actually use the products. Otherwise, you are simply buying for the sake of it, which is a waste of your hard-earned cash.
Buy a train ticket at the station on the day of travel and the price is likely to give you a shock - especially if you are travelling a long distance at a busy time of day.
However, you can cut the cost of train travel by 50% or more by going online and making the purchase beforehand - especially if you book 12 weeks in advance, which is when the cheapest tickets are on sale.
Other ways to reduce the price you pay include avoiding peak times and taking advantage of so-called carnet tickets, which allow you to buy, for example, 12 journeys for the price of 10.
Most High Street banks offer packaged accounts that come with monthly fees ranging from £6.50 up to as much as £40, with a typical account charging about £15 per month.
Various benefits, such as travel insurance and mobile phone insurance, are offered in return for this fee. But whether or not it is worth paying for them depends on your individual circumstances.
It is reasonable to assume that if you take out a mobile phone contract at £30 a month for 24 months that's exactly what you'll pay unless you exceed the tariff. Yet mobile phone providers have come under fire for a snag buried in the small print – a clause to allow mid-contract price rises.
Prices are rising by a median of 81p a month and 70% of consumers are completely unaware off this sneaky move, according to Tesco Mobile, so be sure to check any new contracts before you sign the dotted line.
Financial service providers always refer to 'typical APR' in advertising to attract customers with favourable rates of interest.
Yet the typical APR on loans and credit cards is only available for those applicants who have a squeaky clean credit record, everyone else could end up with a much higher rate. For example, under EU rules, credit card providers only have to provide the typical APR advertised to 51% of applicants.
So always consider this when applying for accounts and products, and if approved – look out the actual APR that you will be charged.
The highest paying savings accounts on the market tend to come with a string of strict terms, which if you fall foul of, result in a drop in interest. Common requirements include paying in a set sum each month and not making withdrawals during a set period.
Make sure to fully understand these terms before opening a savings account and if you choose an account with a six or 12 month bonus, remember that this will plummet when the bonus period ends.
Cashback credit cards that pay you a small percentage each time you spend on the card are full of loopholes in the small print. All have a maximum spend, but many have a minimum spend too.
For example, the Sainsbury's Cashback Low Rate card advertises that it offers users 5% cashback for the first three months. However the 5% cashback is capped at £50 a month. A further 5% cashback is subject to you spending £500 a month on the card (£250 of that at Sainsbury's).
Attempt to repay your mortgage early and you may be greeted with a hefty fee in the form of an early repayment charge. These penalties vary from lender to lender and even deal to deal, but are typically be around 10% of the outstanding balance.
Details of any early repayment charges should be clearly outlined in your mortgage contract but it is worth double-checking with your lender before you try to make a payment.
Insurance is an incredibly complex area of personal finance and different forms of cover are riddled with different hitches that make it crucial to read the small print. Failure to do so could lead you to pay for a product you would be never be able to claim upon, or unknowingly do something that invalidates your claim.
Always buy the right level of cover for your needs and pay close attention to any exclusions in the policy wording. For example, many travel insurance policies for winter sports won't pay out for treatment of injuries incurred while under the influence of alcohol.
Think a credit card can't do any damage at home in your drawer? Think again. Some credit and store cards charge a dormancy fee if you don't use them regularly.
For example, all Santander-issued store cards, including Topshop and Laura Ashley cards among others, charge a fee of £10 if you remain in debit for three consecutive months.
Exceed the monthly usage allowance in your broadband deal and you could be hit with a huge fee. Common with the cheapest broadband deals on the market, penalty charges for going over your contracted limit can push your bills up even higher than if you paid for a deal with unlimited usage.
According to Talk Talk, some households are being forced to pay an additional £40 per month for exceeding their usage allowance. BT for example, charges £5 per every 5GB extra used.
Familiarise yourself with the download limit in your package and the penalties for exceeding it, decide whether you are better off with an unlimited deal.