An update posted to the bank's Facebook page at 5.30pm said the tech team believed they had found the issue and were working to resolve it.
"Most card transactions are now working but we have yet to implement a comprehensive solution.
"We still don't have an ETA for when things are due to be back to normal so we continue to experience a widespread systems outage affecting access to our website, Westpac One online banking, some card services and our contact centre.
"We apologise for the inconvenience and are working to fix this issue as soon as we are able."
Final update: The outage has been resolved and all systems are back online and operational. Payments are flowing through...
Posted by Westpac NZ on Sunday, May 10, 2020
One customer commented that they were caught out at the supermarket after their card declined.
"I have a family to feed and had to leave my groceries in the trolley at the supermarket. In this day and age you'd think this could be sorted quick smart ... we're hungry."
For some, their card services were working again, but not for all.
Those that were unable to access their cards were advised to try using a credit card.
But others are still locked out of the website and banking app, only to see a message flash across their screen as they try to log in.
"Something went wrong," the message reads.
"We were unable to complete your last request. Please try again later."
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