A couple who questioned their Aldi bill said they were left "humiliated" by staff as they were forced to unpack their shopping.
Daniel and Pamela Murray queried the price of their shop when it came to over £60, having only popped in for a few things.
They claim the cashier told them she had scanned everything they had and £66 was their total.
But Daniel and Pamela requested to see the bill and discovered they had been charged for a 'special buy' portable gas grill they did not buy costing £39.99.
The couple, both in their 60s and from Rhyl, North Wales, said the manager of the Marina Quay store was called and they were made to unpack their shopping in front of a queue of customers.
Speaking to North Wales Live, Daniel said: "We'd only popped in for a few things and there was only one till open at the time.
"We loaded our items onto the belt but we got a shock when the cashier told us the bill was £66.
"I said: 'That can't be right, we've only got two carrier bags.'
"I asked her to print a receipt and it was showing £39.99 for a portable gas grill we hadn't even bought.
"The manager and a security guard was called over and we had to unpack all our shopping so they could check the item wasn't there.
"By this time a big queue was forming and we felt so embarrassed and humiliated. We didn't even get an apology."
Daniel said the £39.99 was eventually deducted with their real bill only coming to £26.
He added: "After the incident I decided to write a letter to the store to say I wasn't happy with how the matter had been handled having not been given an apology.
"I also wanted to warn them that maybe something had been coded up wrong, in case this happens to someone else who might not notice being overcharged before it's too late.
"How would people who've left the store prove they hadn't bought it?
"Anyway, I didn't get any response to my letter, nor to a further email that was sent to the Aldi head office.
"We don't want anything, we just don't think it's very good customer service."
An Aldi spokesman said: "We have apologised to the family for their experience at the Rhyl store."
