A debit card glitch that meant an undisclosed number of Barclays customers were billed twice for some transactions has been fixed and those affected have now been refunded, according to the bank.
Earlier a tweet from Barclays UK confirmed the problem, saying the lender was "are aware of some payments being duplicated this morning".
But by Monday afternoon the bank had corrected the problem and said all affected accounts had been credited.
An emailed statement from Barclays said "this matter has now been resolved and all customers have been refunded, with no one left out of pocket".
The bank did not provided details of what had caused the problem.
This is the latest payments problem to affect British consumers after a problem with Asda's card machines on Sunday caused long queues at checkouts across the country.
The supermarket later apologised to customers and said it was working on fixing the problem.
Other UK banks have seen customer services impacted this year, including HSBC which was hit by a denial-of-service attack that temporarily shut down its online banking service in February.