A customer thought he needed his eyes testing again after he saw a till displaying a bill of £4bn for a bottle of eye drops at Specsavers.
Martyn Chidlow had recently had an eye test and examination at his local store in Wrexham, north Wales, when he returned for the eye drops to stop his eyes getting dry.
When he saw the figure of £4,031,626,711.51 pop up on the till - the equivalent of more than half the annual NHS bill for Wales - instead of the expected £9.95 price, he said he "couldn't believe my eyes".
The 55-year-old father-of-two, from Wrexham, said: "I'd recently had my eyes tested and I'd popped in to get the prescription and to get the eye drops because I get dry eyes.
"The girl scanned the drops and then she was having a bit of a nightmare as she scanned it again and this price popped up.
"I couldn't believe my eyes when I saw the price on the screen, I'm glad I'd just had my eyes tested.
"I said to the assistant 'I was going to pay by cash but I guess I'll have to use my card'.
"I caused quite a stir as I just started giggling, I felt sorry for the lady at the till as she was trying to sort it out.
"She was really good and got it all sorted very quickly. It wasn't human error, it was just a problem with the computerised till."
The eyedrops are priced at £9.95
The cameraman added: "I joked later with my wife that I was glad I'd been to Specsavers or I might not have spotted the mistake."
A spokeswoman for Specsavers said: "Our in-store scanners are very sensitive and in this instance appear to have processed the customer's ID number, instead of the product's barcode.
"The mistake was sorted in moments - looks like our scanners should have gone to Specsavers."
Should have gone anywhere else more like.
