The Financial Ombudsman Service has criticised banks for not dealing with money transfer mistakes well enough, according to the BBC.
It received 688 complaints about money transfers in the last financial year, compared with 529 the year before - and less than half of this year's cases went in favour of customers.
So what's going wrong?
When you transfer money from one bank account to another, you enter account details and a sort code, but if you enter the wrong details - even only one digit incorrectly - your money could end up in the wrong person's bank account.
Natalie Ceeney commented in 'Ombudsman News' that "in some cases the money can be recalled, but this relies on the customer and the financial business acting quickly".
Many people wonder whether you or the bank would be responsible if you transferred money into the wrong bank account by accident, but in reality it depends.
For example, a dad who transferred £1,000 to his daughter, but mistyped her account number by one digit, got nothing from his bank because the ombudsman ruled it was his mistake and that the bank "had displayed a clear message on the screen at the start of the online payment process".
Whereas in another case, where a man used a list of 'recent transactions' on in his online bank account to transfer money to his mother, but clicked the wrong recipient, the ombudsman sided with him and he was refunded, because his bank didn't show him a "final confirmation" page when he made the transaction.
A spokesperson for thinkmoney commented: "It's a good idea to double and triple check the account details of anyone you are transferring money to. Our customers can also ask our Money Managers to help with any money transfer, which should help to minimise mistakes."