The chairman of Royal Bank of Scotland, the parent company of Ulster Bank, has warned that the problems at the bank could continue into next week.
Technical problems with the bank's payment processing systems have left thousands of customers unable to access their accounts for over two weeks.
Ulster Bank is expecting increased footfall at its branches today as the continuing technical issues impact even more customers.
Ulster Bank's CEO says situation is unacceptable
In a letter to customers today, Ulster Bank's chief executive Jim Brown has again apologised and said the continuing situation is unacceptable.
He said clearing the backlog is progressing at a slower pace than they had wanted.
The letter comes as 48,000 Ulster customers have difficulties getting their monthly social welfare payments into their accounts.
Representatives of the Central Bank including the Director of Consumer Protection Bernard Sheridan will appear before the Oireachtas Finance Committee tomorrow followed by Ulster Bank on Thursday.
Today, the Department of Finance said the situation must be resolved as a matter of priority.
Meanwhile, the Consumers Association of Ireland has received thousands of complaints from Ulster Bank customers, frustrated with the poor quality of information they are receiving from the bank.
90 branches across the island of Ireland have extended their opening hours until 7pm this week to help customers.
Senior figures from Ulster Bank's parent company, Royal Bank of Scotland, have come to Ireland to deal with the fallout. Chief executive Stephen Hester met the Financial Regulator Matthew Elderfield in Dublin yesterday.
RBS chairman Phillip Hampton, who met politicians in Belfast, said he understood customers anger
"I apologise to all of our customers for the inconvenience and difficulties we've caused them. It should never have happened. I don't think we will fix it by the end of the current week. Hopefully as we go through next week, we will absolutely break the back of this," Mr Hampton said.
