Shoppers are being urged to check their bank accounts after Tesco mistakenly charged thousands twice for the same items.
The double debit has affected in-store customers and those using Tesco petrol forecourts, but has not hit online shoppers.
Britain’s biggest grocer blamed “a technical error” and said it was working to refund accounts.
It said it would also look at cases where customers had gone into the red and been hit with bank charges as a result.
The problem was highlighted by consumer website MoneySaving Expert.com after shoppers used Twitter to vent their anger.
One fed-up shopper, who has been waiting for a refund since the weekend, tweeted: “I was charged double on Saturday for my grocery – bank is still showing payment as pending.
"Any idea when this will be resolved?”
MoneySavingExpert investigations editor Steve Nowottny said: “Tesco says it’s automatically refunding customers within a day but if you’ve been double-charged, you should make sure the refund comes through.
"If you’ve been left out of pocket … complain to Tesco.”
A Tesco spokesperson said: “We’re sorry for any inconvenience and we want to reassure affected customers that they will only pay for their purchases once and any duplicate transactions will be reversed.”
