Ulster Bank is to extend opening hours at 51 branches in the Republic and 42 branches in Northern Ireland today and tomorrow.
Today marks the third week of payments backlog at the bank.
The bank said the majority of balances should now be updated to July 5 and it expects this will be the last week of significant delays for customers.
The Central Bank's Director of Consumer Protection has said he can not give assurances that the payment issues which have affected Ulster Bank customers over the past three weeks could not occur at another Irish bank.
In an interview with RTÉ's This Week programme, Bernard Sheridan said the Central Bank had contacted all Irish banks and reviewed their payment and technology systems.
"Clearly we can not give an assurance that it is never going to happen again. We have already gone back to all the other banks to highlight this issue to them to make sure they're reviewing in the light of what has happened," he said.
The Central Bank is investigating the causes of the technical problems which affected over 500,000 Ulster Bank customers leaving some unable to receive payments such as salary and social welfare benefits into their accounts.
The investigation has yet to uncover the exact cause of the problem with Ulster Bank's information and technology systems. Mr Sheridan said when the causes were identified all Irish banks would have to address any issues highlighted by the investigation.
Customers of Ulster Bank's parent company Royal Bank of Scotland and its subsidiary NatWest in the UK faced similar problems last week. Ulster Bank customers, however, faced additional delays in seeing their account details updated because the technical problems at RBS and NatWest were resolved before those at Ulster Bank.
Bernard Sheridan said the Central Bank, in conjunction with the UK financial regulator the FSA, would be carrying out an investigation into RBS' handling of the affair.
Ulster Bank will have to agree a restitution plan with the Central Bank to compensate its customers. The Central Bank also has powers to take enforcement action and impose fines on Ulster Bank if it is found to have breached financial regulations.
