A Christchurch shopper is urging people to check their bank statements after being overcharged five times.
Eftpos company Windcave has admitted it is at fault for BNZ customers being overcharged on Saturday.
An update on its website said wrong charges were made for some merchants processing the Windcave-BNZ link for an hour on Saturday afternoon.
Simon Hunter brought a Christmas tree worth $135 at The Warehouse on Saturday, it wasn't until later he realised he had been charged five times that amount.
Hunter said the shopping chain's head office told him that thousands of shoppers were affected nationally by the computer glitch.