Between 15 August and 22 September 2019, Mastercard and VISA payments in a store in Rhyl, North Wales, were not processed by the company.
A sign displayed in the store told shoppers that, “If you were here during this period and paid on card you will see the transaction complete and appear on your bank statement from Thursday, October 3.”
"Purchases on AMEX were not affected.
"We apologise for any inconvenience this has caused and want to assure customers that card payments are now being processed at this store as normal."
But not all customers were happy, with some complaining that they were being hit with five weeks of bills in one go.
An Aldi spokesperson said: “Due to a technical error Mastercard and VISA payments made at our Rhyl store between the 15th August and the 22nd September were not processed.
"Customers who made a payment on card during this period will see the transaction appear on their bank statement from Thursday 3rd October.
“We apologise for any inconvenience this has caused and want to assure customers that card payments are now being processed at this store as normal.”
Aldi has advised anyone who shopped at their Rhyl store between 15 August and 22 September to check their bank accounts as a precaution.
The company have asked anyone impacted by overdraft charges because of it to contact them.
You can contact Aldi's customer service desk on 0800 042 0800.