Confused ASB customers have been left red-faced at checkouts after a banking fault saw their Eftpos cards declined, despite having money in the bank.
Customers are also locked out of their online banking, seeing only an error message flash across their screens when they try to log in.
One customer posted online about their "embarrassing" experience at the supermarket checkout, where their card was declined as they did their weekly food shop.
"It was my weekly supermarket trip and my card [was] declined," he posted on Facebook.
"The ASB mobile app isn't working and I can't even see my balance. I hope they get it sorted by tomorrow."