Martin Lewis has warned that people could be owed thousands of pounds from their bank.
The Money Saving Expert spoke about the issue on his ITV Money show on Thursday.
Martin said that millions of people could have been mis-sold their bank account.
He said there were lots of bank accounts that people pay for that usually come with insurance or other benefits.
Many people choose these accounts, but others could have been mis-sold the account and in that case they could be owed thousands in charges.
Martin said: "Were you told you had to get it to improve your credit score or for your mortgage or overdraft, you were probably mis-sold.
"Did it come with insurance but it was invalid for you, for example didn't cover your age or pre-existing medical conditions, you were mis-sold.
"Was the price hiked up and they didn't tell you? You were mis-sold.
"You can reclaim the charges if you were mis-sold, there are lots of online tools to help you claim, don't pay anyone to do it.
"If your claim gets rejected, take them to the ombudsman."
Martin's co-host Angelica Bell then read out a tweet from someone who had reclaimed their charges following Martin's advice and had managed to get £1,400 back from Natwest.
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Martin also pointed to another way to reclaim cash from the bank and that was if you had been pushed into financial hardship by bank's overdraft charges.
He said this was more uncommon now, because overdraft charges had been banned, but that people could still claim if they had been pushed into hardship.
