TSB told a customer he had until 2:30pm to find extra money, after it blocked his wages and stalled his bills on Friday morning.
Robin Fletcher, 33, woke up to a text from the bank stating that he had insufficient funds - explaining that he would incur fees for bounced payments if his account wasn't topped up by 2:30pm today.
"I have several standing orders set up to cover money that I owe to friends and family," he told Mirror Money.
"The bank basically said that because I haven't been paid, I don't have enough funds, and so I risk being hit by extra charges."
Robin, who is celebrating his 33rd birthday today, had booked the day off work to attend a friend's funeral.
He described the bank's blunder as "throwing a spanner in the works' on the day he "least needed it".
After receiving the text at 8am, Robin called up his employer, only to be told that they'd followed all procedures on their end.
"They said several employees with TSB had also called about a similar issue - so I decided to contact the bank instead."
"I tried to contact customer services, but after 40 minutes in a queue, I gave up," Robin said.
"To make matters worse, the app has been down too. It's been buffering since 8am."
"I then called up my local branch - only to discover that they had no clue what was going on, either.
"I asked about an emergency payment - but the advisor was unaware of what this was. I told her to check the news - it was obvious that staff hadn't been consulted on the situation. She was equally in the dark."
Robin, who works as an agency worker for the Royal Mail said today's failure will result in him closing his account for good.
"I have an overdraft which I'll keep paying off, but I'll take my wages elsewhere," he said.
"I don't want them making any money out of me."
The legacy customer, who joined in 2016 after the bank broke ties with Lloyds, said he was also affected by last year's IT meltdown.
"They gave me £100 in compensation," he said, recalling the incident that affected more than 1.9million account holders.
He's now had to borrow money from his partner's Jobseeker's Allowance to help cover the money he owes friends and family, as well as his expenses for the next 24-hours.
Commenting on today's failures, a TSB spokesman said: "Some payments into TSB accounts have been delayed overnight and we are working to process these as soon as possible today.
"We apologise for the inconvenience this has caused and will ensure customers are not left out of pocket."
