The Eftpos electronic payment network has been restored after it crashed for nearly three hours on Monday. Shoppers abandoned full trolleys in supermarkets and some businesses gave away food and drinks because of the outage.
Hungry kids cried, "old ladies" yelled and there was reportedly "complete chaos" in one supermarket when the Eftpos system failed nationwide.
The electronic money service was not restored until 11pm.
The network tweeted: "Eftpos should be back online for merchants experiencing time-outs on transactions."
Paymark spokesman Paul Brislen said the outage occurred at 8pm when "a component within the Paymark network experienced connectivity issues".