Furious customers hit out at the outages on sociale media.
"Westpac's payment processing is down. No ETA on restoration. Phone dude told me to try again in an hour," wrote one disgruntled customer on social media.
"What is happening with Westpac!!! We have a grocery store and none of our eftpos is working customers are leaving!" wrote a business owner.
One shopper tweeted to Westpac saying all its systems were down and customers were being asked to pay cash instead of card.
"We are currently aware of the issue and our team is working to get this resolved ASAP," a spokesman for the bank responded on Twitter.
A Westpac spokeswoman told news.com.au the problem is now under control and all systems should be back to normal.
She said the outage lasted one hour — from 11.59am to 12.58pm (AEST).
"We want to sincerely apologise to customers," she said. "It's a terrible day for this to happen."
ANZ has also copped hammering on social media.
"App still not working. Makes it hard to shop for the sales," wrote one customer.
"Just tried to log in to the app but it won't recognise my fingerprint or my pin code," wrote another.
One customer told 3AW his app shows an error message which reads: "Something went wrong, please try again later".
"I waited about 20 minutes on the phone and they said it's down nation-wide," Jan said.
"They don't know when it's going to be back up and running."
Both crashes come as more than half of Australia expected to be on the hunt for sales today — causing roads in major cities to become gridlocked.
December 26 is still the nation's supreme shopping event, despite November's Black Friday and Cyber Monday offering large discounts.
News.com.au has approached ANZ for comment.
