RBS boss says software upgrade caused problems
25 June 2012 Last updated at 14:42 BST
The boss of RBS has told the BBC that a software change was responsible for the widespread computer problems affecting millions of customers' bank accounts.
Stephen Hester said "it shouldn't have happened and we are very sorry".
The software upgrade failed last week, and although it was put right it caused the huge backlog of transactions that are still being sorted out.