Lloyds Banking Group has told customers that many debit and credit card users who made purchases on New Year's Eve may have been double charged in error.
Around 200,000 people are thought to be affected by the problem which occurred after the wireless terminal system used to process card payments recorded a "system error".
It's thought that many different types of card could have been affected by the error in the systems which are provided by Lloyds TSB Cardnet. Users will see their transactions appear twice on their card statements.
One credit card user who was out celebrating on New Year's Eve used a Tesco Mastercard to pay for a restaurant bill.
On January 3 he noticed the transaction on had appeared on his account and he noted the same transaction appeared again the following day, January 4.
The restaurant in question has confirmed that they are attempting to ring all the customers to alert them to the fault in the card transactions.
Speaking with BBC News, Lloyds Banking Group apologised for the error and inconvenience caused to users by a technical area.
The Group said, "Duplicated transactions have been reversed and card holders are being reimbursed."
They also said that any individual who had been charged by their card company as a result of the double-charging should contact Lloyds where, "We will consider all reasonable and evidenced requests for reimbursement," they said.
A helpline has been set up for users affected by the error. The number is 01268 567100, option 4.