TSB warned customers before the weekend that some of its online banking and money transfer services would be "unavailable" while it completed maintenance and upgraded its IT systems, which were once linked to its former parent, Lloyds Bank.
The message that was being encountered by users stated that the access to the internet banking is being restricted and that this is being limited to once to make sure that the customers get decent service.
Those who could access their accounts flooded social media with reports of rogue credits and debits, some timed for decades ahead of the current date.
There have been a growing number of customers reporting desperate circumstances because they have been unable to access their funds - since last Friday in many cases.
CEO of TSB Paul Pester has publicly apologised as the IT problems plaguing the banking group continued into their fourth day.
Later, it claimed that its digital services were back up and running.
The team will report directly to TSB's embattled boss, Paul Pester.
Shujun Li, a cybersecurity research at the University of Kent, said the main issue was not the initial failure - modern IT systems are too complicated and dynamic to be totally bug-free, he said - but because of the bank's poor risk management.
For customers of Ulster Bank, which is part of Royal Bank of Scotland, the glitch will bring back memories of one of the banking industry's biggest-ever IT failures.
The results were mostly overshadowed by the bank's IT problems.
Hundreds of customers have taken to Twitter to express their frustration at poor communication from the bank, with many demanding compensation for the stress caused.
The Reg has asked TSB for an update and will update this article if we get it. ®. After this week's debacle, it would be extraordinary if they were to receive anything extra at all.
It could also have long-term implications for the bank.
TSB, the bank floated out of Lloyds in 2013 and snapped up by Spain's Banco Sabadell less than two years later, has called in IBM in a bid to iron out its re-platforming project that went catastrophically wrong this week.
The bank's chairman, Josep Oliu, boasted that the exercise had proven the bank's "technological management capacity, not only in national migrations but also on an worldwide scale". But then, perhaps he couldn't get through on the phone either.