Nine days later Mrs de Cleene went through the checkout with another bottle and said she was again overcharged.
"I thought it couldn't possibly happen again nine days later. They were still charging $6.39."
Mrs de Cleene was again refunded the difference, but said she was told staff could not fix the mistake because price changes had to be made at parent company Foodstuffs, in Auckland.
"New World should give the money back by making a donation to a local charity," she said.
Brookfield New World has donated $250 to Mount Maunganui Surf Life Saving Club.
Mrs de Cleene said she thought the donation was generous and was more than satisfied with the way the mistake had been dealt with.
Foodstuffs, the overarching company of owner-operated New World supermarkets, confirmed the mistake.
Antoinette Laird, head of external relations, said the correct price of the milk was $5.29 - up 10c per litre from $5.09 due to an increase in pricing from suppliers in late January.
"The incorrect price had been loaded in the system, so when it was checked by store staff they were unaware that it was wrong," she said.
When asked why the mistake was not fixed after the first and then the second time it was pointed out, Ms Laird said: "It's been a busy time of year, and a couple of team members have made an honest mistake and not communicated there was an error, which has now been corrected."
She said the store would be happy to refund any affected customers.
Ms Laird said Mrs de Cleene had been misinformed about the ability of store staff to correct the pricing and the team had since been spoken to so the mistake was not repeated.
