NATWEST, RBS and Ulster Bank customers have been left high and dry after a major technological glitch has left them unable to use debit or credit cards.
The problems began at about 6.30pm this evening with social media buzzing with reports of cards being declined en masse across the country.
One of those affected was Mick Plunkett from Derby.
He was in the Cosmo restaurant when his card was declined.
He said: "It was so embarrassing. There were about eight people behind me.
"My wife went out to see if she could get some cash out but that wouldn't work either.
"Luckily we had a credit card that we could use.
"As we were walking down St Peter's Street there were a number of people who were unable to get cash out as well. Some of them were trying to get home to Leicester."
An RBS spokeswoman confirmed the problem.
"We are aware of the technical issues being experienced by customers and are working to get them fixed urgently," she said.
"We apologise to customers for the inconvenience caused."
The meltdown comes amid a day dubbed Cyber Monday, which is typically when the highest amount of online transactions are expected so shoppers can meet pre-Christmas delivery deadlines.
