TSB computer issues attract regulators' and MPs' attention

A Financial Conduct Authority spokesperson told Credit Strategy the regulator was “aware of the problem and liaising with the firm”.

Similarly, the Information Commissioner’s Office said it is “aware of a potential data breach in relation to the TSB and are making enquiries”.

The bank has also entered the crosshairs of the Treasury Committee, with chairwoman Nicky Morgan writing to Paul Pester, chief executive of TSB, to find out what has gone wrong and the extent of the failure.

“The reports of unauthorised transactions, access to other customers’ accounts, and failures of in-branch services have all the hallmarks of an IT meltdown," she said. “This is yet another addition to the litany of failures of banking IT systems. Potentially millions of customers could be affected by uncertainty and disruption. Warm words and platitudes will not suffice."

Some customers were left unable to access their accounts or make payments, while others were shown incorrect information, and in some cases the details other people’s accounts.

The bank warned its customers that it was carrying out upgrades at the weekend between 16:00 BST on Friday and 18:00 on Sunday, but problems persisted leaving some customers concerned about paying bills and accessing cash to pay for essentials.

However, Pester has today (April 25) taken to Twitter to confirm the banking app and online service is now back to running as normal.

TSB has issued an apology via its website, with details about which services are affected and what customers can do, while chief executive Pester also issued an apology.

He said in a series of tweets: "This isn’t the level of service that we pride ourselves on providing, and isn’t what our customers have come to expect from TSB, and for that I’m deeply sorry.

"We’re still seeing issues with access to our digital services. One of the steps we need to take to resolve this is to take our mobile app and online banking down for a few hours."

The issues stem from when TSB split from Lloyds Banking Group. It continued to rent a banking platform from Lloyds while it constructed its own, Proteo4UK.

That system was ready to go live over the weekend as it moved its customers’ data from the old platform to its new one.

Despite the issues, Josep Oliu, chairman of TSB owner Banco Sabadell hailed the migration to Proteo4UK as “an excellent starting point for the organic growth of the business and the improvement of TSB’s efficiency”.

He added: “With this migration, Sabadell has proven its technological management capacity, not only in national migrations, but also on an international scale. More than 5.4 million customers are now integrated into the new platform, which allows us to grow in a market as mature and highly competitive as the UK market.”