Royal Bank of Scotland (RBS) customers were unable to make card payments or withdraw cash as the bank experienced its latest IT outage.
Customers of both RBS and Natwest were affected by the 'technical problems' on Monday evening, with online banking and mobile apps also unavailable.
The bank subsequently apologised to its customers via a message on its official RBS and Natwest Twitter accounts.
"We're aware of some technical issues and are working hard to fix them. Sorry and thanks for your patience," the statement read.
The outage occurred on 'Cyber Monday' - expected to be one of the busiest online shopping days of the year - with irate customers venting their frustrations on Twitter.
One customer of Natwest, Rosie Marks (@rosie_marks) tweeted: "Thankyou@NatWest_Help for causing me to cry a lot in the middle of a printing shop in Kings Cross when my card was rejected."
Meanwhile Ben Dummer (@casatichap) said: "#natwest why don't they spend the £500 million in bonuses on IT instead? Idiots."
The outage is the latest systems failure to befall the banking group. Last year a high profile IT meltdown led to millions of customers being unable to access accounts after a botched upgrade made to batch processing software CA 7 from CA. The incident is currently the subject of an investigation by the Financial Conduct Authority.
The bank suffered more IT related problems this year, with as a hardware problem blamed as Natwest customers were unable to make online banking transactions, cash withdrawals or debit card payments in May.