Ulster Bank executives brief Stormont on computer failure
Ulster Bank's ongoing problems are expected to be fixed by 16 July, executives have told the NI Assembly.
Thousands of customers in Northern Ireland and the Irish Republic are being affected by a computer failure at the bank's parent company RBS.
Senior members of the bank have been at Stormont to explain the crisis to a committee of assembly members.
Jim Brown, Ulster Bank Group CEO, said next week would be the final week of any significant delays for customers.
He offered an "unreserved apology for the disruption this issue has caused our customers".
"It is unacceptable and our customers would expect more from us," he told the Enterprise Committee.
He said RBS would carry out a detailed investigation of the problems and would publish the findings.
"Initial reviews indicate that the problem was created when maintenance on systems which are managed and operated by a team in Edinburgh caused an error in our batch scheduler," he added.
"The error caused automated batch processing to fail on the night of Tuesday 19 June.
"The knock-on effects created significant delays and required substantial interventions from our team."Compensation
Mr Brown pledged that customers would not lose money as a result of the problems.
"Our intention is that customers - it doesn't matter whether it's Ulster Bank or other banks' customers - won't be out of pocket as a result of this incident," he said.
"We are also looking at whether we should be making other compensation over and above that."
He added: "We expect to have the policies finalised over the next few days. The whole theme here is to do this as quickly and painlessly as possible.
"The funds are in place to be able to do this as soon as is necessary."
Chris Sullivan, the CEO of Corporate Banking at RBS, said 100 people had been brought to Northern Ireland to work on the problems and staff have been redeployed to the "frontline".'Appalling episode'
Sinn Fein assembly member Daithi McKay said the crisis had been "an appalling episode".
"I think it's a great shame that you cannot stay with representatives of the public here for more than an hour, I think you should make more time speaking to us this morning.
"I think as well in terms of contingency planning, it's one of the worst examples I've ever seen."
The DUP's Stephen Moutray said given the "untold misery" of customers he would like assurances from Mr Brown would not take a bonus, customers' credit ratings would not be affected, and that the bank would open on the 12 July holiday.
Mr Brown said the bank was reviewing whether to open on 12 July and was working to ensure customers' credit ratings weren't affected.
He said he would review whether or not to take a bonus if it was decided he deserved one.'Missing money'
Earlier, a small business owner had told the BBC he was unable to locate £50,000 in electronic payments, but the bank later told him the money had been found.
RBS executive Mr Sullivan denied money was going missing.
"The money is going into the bank - it's just not showing in their accounts and we're about five days behind in terms of catching up," he said.
Mr Sullivan, who is head of RBS UK Corporate Banking, said an independent review of the IT failure would be held.
"I don't think any of us are IT experts, so the board of RBS has commissioned independent consultants to look at the whole incident, tell us what went wrong and what we should do," he said.Processes
While the problems with RBS and NatWest accounts have been resolved, Mr Sullivan denied they had been given priority over Ulster Bank customers.
"It's purely because of the way the system is built - it was originally an RBS system, then NatWest came along and Ulster Bank was put on later, and those processes have to run in that order," he said.
Prime Minister David Cameron has said the crisis is "unacceptable".
Mr Cameron said he had received assurances that RBS would reimburse Ulster Bank customers for penalty charges or overdraft fees, or anything else that was incurred because of the difficulties.