Frustrated TSB customers are continuing to be locked out of their accounts as the bank’s IT fiasco enters a second week.
Some have suggested the system is “going from bad to worse” as they are denied access to online banking and the bank’s mobile app.
Worries over payments also remain as error messages are shown to some customers trying to move money.
The bank said it was “working around the clock” to fix the problems.
The debacle began when TSB shut down services for two days from the evening of Friday, 20 April to move customer data to a new IT system managed by its Spanish owner Sabadell.
As soon as the new system was switched on, customers reported seeing other people’s account details alongside a range of other difficulties.
A week on, the bank – which has called in experts from computing giant IBM – again closed online and app services during the weekend in order to try to fix the ongoing issues.
The bank said on Sunday that internet banking and business banking were operating again, but accepted that some customers were continuing to have difficulties.
Early on Monday, a spokeswoman said that the problems had still not been solved although there has been no official update as yet from the bank. It has continued to apologise to complainants through its social media channels with a vow to work all hours to solve the problems.
Customers have expressed their fury, with some looking to switch to a different bank despite attempts by TSB to keep them with promises of higher interest rates on its current account.
One of the major worries among the 50% of customers who have been able to access online banking is that some of their accounts appeared to have vanished.
One wrote on Facebook that a savings account had vanished and that it did not show up on the system in a branch.
Another saw the potential upside of such a failure, by joking: “I’m guessing I’m now mortgage free as no mortgage account showing on online banking. Thanks for paying it off TSB, didn’t expect as much as that in compensation for the constant account muck ups!”
The bank has warned that fraudsters may be attempting to use the confusion to trick customers out of money.
It said that some were receiving emails and tweets claiming to be from TSB, but pointed out that the bank would never ask for security details such as a Pin or full password, and would only use its official Twitter and Facebook channels.
The bank’s chief executive, Paul Pester, is coming under considerable pressure to explain how the system has failed.
He wrote to Nicky Morgan, who chairs the influential Commons’ Treasury Committee, on Friday to update MPs on the situation.
Mr Pester has promised that no customers will be left out of pocket as a result of the saga.