Shoppers' rights and your "statutory rights" are often misunderstood by both consumers and shop staff alike. So if you're planning to return something and ask for a refund, it pays to arm yourself with all the correct information.
The bad news is if you simply don't like a present you've received or change your mind after buying something, you don't have any rights to a refund.
Some shops will exchange items – clothes in the wrong size, for example – or issue a credit note, but generally they don't have to.
The exception is if a shop has a published returns policy. If it does then it forms part of the condition of sale, and is enforceable in court.
Some shops are more generous than others when it comes to their returns policies for Christmas presents. Marks & Spencer, for example, says if you bought something between 1st October and 12th December you can get an exchange or refund up until 15th January.
You'll need to provide proof of purchase or a gift receipt if you want a full refund or exchange. Otherwise you will be offered a credit note for the value of the goods at the current selling price.
Meanwhile John Lewis has no set time limit for the return of unsuitable products all year round. You'll need to provide proof of purchase or a gift receipt to get a full refund or exchange.
It's different if you buy things online. Under Distance Selling Regulations, you have seven working days from the date the item was delivered to cancel the order and return the item, even if it's just because you don't like it.
The retailer should then refund you within 30 days of you cancelling the order. However if you're returning an unwanted Christmas present, it's likely the buyer, and not you, will receive the refund.
However, the exception here is if the goods were personalised. If you get jewellery inscribed or pay to get a holiday photo made into a canvas print, for example, you won't be entitled to a refund.
If you buy something and it turns out to be faulty, you have the right to expect the shop to sort it out either by replacing the product or giving you a refund. Some shops will try to refer you back to the manufacturer but this is wrong: it's the shop that you have the contract with.
The Sale of Goods Act says that goods must be of "satisfactory quality, as described, fit for purpose and last a reasonable length of time".
So if you buy something that doesn't work you have the right to a refund or repair.
The biggest disagreements tend to be over what a "reasonable length of time" means as it's quite subjective. I successfully argued with Dixons that a £600 TV should last longer than two years when mine broke down – and they coughed up some money for a new one.
Some shops might also try to refuse the return of faulty sale goods, but this is wrong. If the goods are faulty you have the same rights whether you bought them full price or at a discount.
Some shops say you can only return goods with a receipt, but this isn't the case with faulty goods. If there's something wrong with them you only need proof of purchase which might be a bank or credit card statement.
However, if it's not faulty, you have no rights unless the store displays conditions saying otherwise. Therefore if store policy says you need a receipt to return something, you'll have to go along with it.
If your stocking was looking a little sparse this year due to goods not being delivered on time, your rights depend on what was agreed when you bought them.
You can only complain if you or the retailer specified (and you can prove) that a pre-Christmas delivery was agreed.
If it was then the goods not turning up on time is a breach of contract and you're entitled to a refund.
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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.