TSB letter error sees some customers receive others’ details

The letters showed the name, address and reference numbers of other customers.

In a statement, TSB said: “We are aware that there has been an issue with a recent acknowledgement mailing. We are working with our third party supplier to understand the root cause of the error and we’d like to apologise to anyone that may be impacted.”

TSB has been seeking to restore its online banking and app services after problems have left customers 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 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 intended to go live over the weekend of April 21 and 22 as it moved its customers’ data from the old platform to its new one.

While TSB says its systems have been restored, the bank’s chief executive, Paul Pester, will appear before MPs on the Treasury Committee for a second time on Wednesday.

Following his previous appearance, the Treasury Committee branded the IT and data migration a “complete and total failure” which “was unacceptable and remains so”.

In that hearing, he said login success rates on the TSB’s app and website were around 95 percent, a typical level for most banks.

MPs heard at the time the migration was the “number one corporate risk” for the bank, with Pester adding it had received 40,000 complaints after millions of customer accounts worth a total of £31bn were moved to the new computer system.

"If there is one decision in my life that I could change it was the decision to go ahead with the migration,” he said. “Clearly that was a terrible decision for our bank, for our customers and for me personally.”

He added customers “won’t be left out of pocket” and that he would not be taking his £2m “integration” bonus.