Ulster Bank denies it broke the law over the tracker mortgage scandal.
3,500 people were wrongly removed from a tracker rate by the bank.
Around 1,200 of those have been compensated so far - only around a third of the total.
Of those 15 customers lost their own homes because of the move.
Executives appeared before the Finance Committee earlier today, and indicated that the number of people affected is likely to rise.
Our Political Correspondent Sean Defoe reports:
Fianna Fáil's Michael McGrath criticised the bank for the lack of progress in compensating customers.
He argued: "The examination started in late 2015 - in your case I think March 2016.
"We're now into February 2018, and they haven't heard from the bank. That's not good enough."
Deputy Doherty said the ongoing compensation process is taking too long – labelling it “pathetic” that only 197 customers were paid their money back in January 2018.
He told senior bankers they need to work harder to ensure those who are out of pocket get their money back:
— Sean Defoe (@SeanDefoe) February 1, 2018
The bank says they hope everyone caught up in the tracker mortgage scandal will get their money back by June.