(AP) — Technicians at the British bank NatWest are trying to fix a software problem which has delayed posting of credits and debits in customer accounts.

Customers of NatWest have complained of including refusals of orders and delays in closing home purchases because money credited to accounts overnight was not appearing on balances.

The problems reportedly are also hitting some customers of Royal Bank of Scotland and Ulster bank. All are part of Royal Bank of Scotland group.

NatWest said Friday that technicians were working around the clock to resolve the problem, which reportedly originated from an attempt to upload an update to programs.

In a statement on its website, the bank said "we apologize to our customers for this unacceptable inconvenience."