Hundreds of thousands of NatWest and RBS customers were this morning facing banking issues as the company admitted "some" payments were "missing" from accounts.
Tax credits and salaries have not appeared as they should, according to complaints from angry customers on social media - with many now worried they will face late payment fees or charges for bills which should have been paid.
Around 600,000 people are believed to have been affected by what the firm called an issue with its "overnight processes" at RBS, NatWest, Ulster Bank and Coutts.
Hundreds of customers have voiced panic on Twitter and Facebook as they had card payments declined in shops, or checked their account to find it empty.
The four banks are all run by Royal Bank of Scotland, which apologised to customers who have been affected via its official Twitter accounts and said engineers were working on fixing the problem as a "matter of urgency".
Some customers are being offered temporary credit if funds are needed urgently, though delays have also been reported on this appearing in accounts too.
However, the company added, there was not yet a timescale for when the glitch would be fixed and people would once again be able to access their money.
RBS spokesman James Abbot said the company would ensure nobody was left out of pocket because of the error.
Many customers have described the issues as "unacceptable" and "disgraceful".
Posting to the building society's Facebook page, Kevin Davey wrote:
Nigel Eatough added: "Wife's wages not paid in due to Nat West technical error today! No info on when it will be resolved? GET IT SORTED! Need to pay bills etc."
And Adele Gibson said: "Absolutely disgraceful yet again Natwest! I hope you resolve this today and compensate your customers accordingly.
"I now don't have enough to get our weekly food shop and I have two children. Well played."
Some customers even reported getting "threatening" texts from the bank for going overdrawn due to bills coming out, when the account should have had sufficient funds.