Data, obtained by Which?, shows the Financial Ombudsman Service (FOS) received more than 1,380 complaints about current account closures in the year 2022-23.
A quarter of the complaints were upheld, according to the data.
Which? says the figures show banks are not always taking sufficient care to avoid closing down the accounts of innocent customers.
Read More : Consumer Group Warns Banks About Wrongly Closing Accounts or Silently Marking Them for Fraud