Stay one step ahead of the fraudsters with our series of articles giving you the lowdown on the scams they use to trick people out of their hard-earned cash - and how to avoid being taken in by them.
This week, the supposedly free trials that dodgy companies offer to trick people into signing up to a recurring subscription.
How does it work?
Fraud of this kind often begins with an advert or pop-up on a social media website urging people to try a product such as a diet pill or a face cream on a "free trial" basis.
Those who want to try the product are then asked to enter their card details to pay a small fee to cover postage and packaging - not realising that by doing so, and failing to cancel within the trial period, they are agreeing to a recurring subscription.
RBS and NatWest alone have helped 37,000 people to cancel payments, which are generally set at about £80 a month.
The banks estimate that scams of this kind have cost their customers more than £2.9 million.
How can I avoid being caught out?
When signing up for a free trial, it is vital to check the terms and conditions of the agreement very carefully.
Subscription details and charges, including what you need to do to avoid being charged in the future, should be explained in these, which is why you should read them in full - even if they are hidden at the bottom of the page.
And if anything seems suspicious, think twice before giving the company concerned your card details.
Terry Lawson, Head of Fraud at RBS said, "Too many of our customers have fallen victim to these scams.
"We want to help raise awareness so that both our customers, and the wider public, look out for unclear or confusing terms and conditions."
If the terms state that you need to cancel by a certain date to avoid paying, it is also crucial not to forget to do this.
I've been defrauded. What should I do?
If you spot a payment you do not recognise, the first thing you should do is contact your bank to find out who is taking the money.
If it is a recurring subscription payment, you will also need to cancel the subscription to ensure no further money is taken from your account.
Lawson said: "If any of our customers think they have accidentally entered into an agreement we'd urge them to contact us so we can help cancel any future payments."
Scamwatch: illegal website fraud
Scamwatch: social media fraud
Scamwatch: pension fraud