Thousands of people across the UK were charged twice for debit card payments following a glitch.
Customers paid twice due to a problem with card terminals run by Cardnet, despite transactions only showing up once on receipts.
The error affected around 5% of payments made on machines on 29 August.
Cardnet is a payment system run by Lloyds Bank and card processor First Data, which handles 1.1 billion transactions a year, including for a wide range of shops, restaurants and businesses in Britain.
This means that Lloyds customers were not the only ones affected, since the machines accept most Mastercard and Visa payments.
Customers will have to check their bank statements for duplicate payments – but they should have been automatically reimbursed.
Lloyds Banking Group said people had been refunded and that the majority of affected transactions involved Visa debit cards.
“We anticipate that refunds to cardholders charged twice will be completed by Tuesday, September 4,” the statement said.
“Cardnet sincerely apologises for the issue and the inconvenience caused, we continue to work closely with all parties to resolve this issue swiftly.”