A bank account error has seen a Martin Lewis fan bag £4,800 back.
The individual in question was able to claim the money after finding out she was mis-sold a packaged bank account.
Packaged bank accounts come with extra costs, usually paid monthly, due to the additional benefits included such as insurance and better savings rates.
There have been occasions where people have been sold the package despite it not suiting their needs.
The fan, Julie, says she was wrongly told that she was not able to cancel her account when she tried to do so in 2010.
The Martin Lewis fan was able to claim back £4,786 as a result of the complaints letter she sent to her bank.
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She used the Money Saving Expert's guide to write a complaints letter, and ended up with a £4,786 refund just 18 days later.
The packages can be mis-sold as banks do not inform the customer of what they are paying for.
It could mean that customers are paying fees they are unaware of or have insurance they can't use.
Julie told MoneySavingExpert: "I tried to cancel my account in 2010 but was told 'it wasn't possible' by the bank.
"Then reading your article I realised that this just wasn't true.
"I followed your advice and used the template letter. 18 days later, I got a refund of £4,786."
MoneySavingExpert offers free tools to help support people who feel they may have been mis-sold a packaged bank account.
In using the service provided by the website, paying a claims firm would not be necessary.
If the bank rejects your claim, you can take it to a Financial Ombudsman for free.
The Financial Ombudsman will not look into the issue until you have contacted your bank and given it eight weeks to respond.
If your claim is successful, you should then receive the monthly fees you paid plus interest.
The amount of money you get depends on how long you were on the plan and how much you paid throughout.