TSB chief executive Paul Pester has told MPs the bank will “come back” from its IT meltdown as he said he took “full responsibility” for the woes.
Mr Pester was appearing before the Treasury Committee, as the hitches persist for a second week.
He said 40,000 complaints had been received over a 10-day period – and promised they would be put right.
Mr Pester added: “Our customers know that I have their interests at heart.”
The chaos started following an IT migration, with up to 1.9 million people using TSB’s digital and mobile banking finding themselves locked out of their accounts.
Mr Pester said: “As the chief executive of the bank I absolutely take full responsibility for what has happened with TSB through this migration.”
Asked if he had failed in the basic duty of a bank to let customers put money in, take money out and keep money safe and secure, Mr Pester said: “I feel we have failed in delivering the level of service we need to deliver to our customers, clearly.
“TSB was built to bring local banking to Britain. TSB was built to reconnect banks to local communities.”
He continued: “I’m deeply sad that the work we have done over the last five years in building TSB as a different sort of bank has been so damaged over the last 10 days.
“But we will come back as TSB. TSB will come back and bring the competition it needs to bring to UK banking.”
Asked why his customers should ever trust him personally again, Mr Pester said: “They should trust me because I will ensure that we bring TSB out of the problems we’re in.
“I’ve given my cast iron guarantee to customers that they will not be out of pocket as a consequence of these problems. And our customers know that I have their interests at heart.”
The issue affecting a number of standing orders today has now been resolved and scheduled payments have been processed.— TSB (@TSB) May 1, 2018
Mr Pester said 40,000 complaints had been received, whereas around 3,000 would normally be expected over a 10-day period.
He said: “Those 40,000 complaints are being investigated. Those 40,000 complaints will be put right.”
Earlier during the hearing, explaining what had happened, Mr Pester said: “You will be aware that the source of these issues was a migration that we did the weekend of April 21 and 22 and over that weekend we extracted all of our customer records for 5.2 million customers – 1.3 billion records – transformed those records and loaded them on to a new platform.
“I’m certainly not downplaying anything about the issues that our customers have faced since then but it’s important to understand that that migration of data went smoothly, the bank balanced to the penny, so the £31 billion worth of customer balances from Lloyds have come across to the new platform and the balances are balanced to the penny.
“The underlying engine of the bank is actually running relatively smoothly. The issues that we are seeing, for which I apologise again to our customers, is that the platform’s ability to support sufficient customers accessing our website and mobile app simultaneously was an issue for us Monday, Tuesday, Wednesday last week.”
He said around 95% of customers were now having success accessing the bank’s internet and mobile services, adding: “We did not see those figures soon after the migration and, as I say, that led to an unacceptable level of performance to our customers.”