British lender TSB has been fined 48.65 million pounds (A$80.21 million) over a botched IT platform migration in 2018, UK regulators said.
The IT upgrade "immediately experienced technical failures", the Financial Conduct Authority (FCA) and Prudential Regulation Authority (PRA) said, resulting in "significant disruption" to TSB's in-person, online and phone banking services.
The regulators found that TSB failed to organise and control the migration adequately, and failed to manage operational risks from its IT outsourcing setup.
TSB was fined 29.75 million pounds by the FCA and 18.9 million pounds by the PRA, receiving a 30 percent discount by agreeing to settle the issue, the statement said.
In a statement, TSB CEO Robin Bulloch apologised to consumers hit by problems during the upgrade.
"We worked hard to put things right for customers then and have since transformed our business," he said.
"Over the past four years, we have harnessed our technology to deliver new products and better services for TSB customers."
TSB's Spanish owner lender Sabadell said in a statement that the settlement would be accounted for by TSB in the fourth quarter.