BOSSES at Ulster Bank have admitted they have under-invested in the computer systems for decades after the bank's payments systems were crippled for the third time in little over a year.
Frustrated customers were left red-faced after their debit and credit cards were declined in shops and others were unable to make purchases on websites during the busiest online shopping week of the year.
Now the head of Royal Bank of Scotland (RBS), which owns Ulster Bank, has admitted that the technology crash was due to spending too little on maintaining its IT systems.
Ulster Bank's electronic-payments system is linked into that of RBS and NatWest in the UK.
Ross McEwan, the newly installed RBS chief executive, said: "For decades, RBS failed to invest properly in its systems."
He said he would be outlining a plan in the new year to step up investment in the computer systems.
Furious Ulster Bank customers were unable to get money out of cash machines, others had to abandon trolleys at supermarket checkouts and drivers had to leave ID at petrol stations for unpaid fuel.
A bank spokeswoman said it was sorry for the inconvenience.
She continued: "We are very sorry for the system issues that affected our customers. If customers have been left out of pocket as a result of these system problems, we will put this right.
"If any customer is unable to resolve an issue caused by the disruption, they should get in touch with our call centres or come into a branch, where our staff will be ready to help."
Asked if affected customers would get compensation, in addition to refunds for out-of-pocket expenses, a spokeswoman for the bank said anyone at a loss should take the matter up at branch level.
The bank has been charging €4 a month for using a current account since the summer, but has no plan to waive fees for December.
It is understood a technical problem at Ulster Bank originated at NatWest, which is the main transaction processor for the RBS group.
Ulster Bank took almost six weeks in the summer of 2012 to get its payment system fully restored. A total of 750,000 customers were affected and people who incurred fees for late payments of loans and mortgages were compensated.
In March this year, it was hit by another IT crash.
The Central Bank said that it, along with the Irish Payments Services Organisation (IPSO), had now implemented an annual risk-assessment exercise with the clearing banks following the huge 2012 meltdown.
A spokesman said: "This annual process will assess the risk-management capabilities across the banks in relation to payments activities. The submissions from the banks will be externally validated."