The bank was forced into a U-turn earlier this month when it wrote to a number of former Ulster Bank tracker customers mistakenly telling them their monthly repayments would have to rise by up to €600 a month.
It later withdrew the letter and said it was a mistake.
Now it has emerged that a small number of former Ulster Bank tracker customers have had the direct debits, which should be paying their mortgages, cancelled.
AIB bought about 32,000 Ulster Bank tracker mortgage accounts earlier this year.
One woman who contacted the Irish Independent said: “I’m one of the Ulster Bank tracker mortgage customers that was ‘sold’ to AIB.
“I just discovered today that they didn’t honour the direct debits that customers had in place to pay their mortgages, despite sending a letter assuring that the direct debits previously in place to Ulster Bank would ‘seamlessly transfer’ to AIB.
“This did not happen. AIB messed up and are trying to cover up, again.”
She said she contacted AIB three days in a row and the bank insisted her payment had gone through.
Despite this, she was told by Bank of Ireland, where she has her current account, that “creditor has not presented for payment”.
“In bank speak, that means that AIB never sought payment. When I called AIB again, almost a week after payment was due and had still not been taken from my account, they changed the narrative and said that they hadn’t taken any direct debits from any transfer customers, oops, and payment was due by the end of the week or it would be considered a late payment.
“The absolute nerve of them,” she said.
She said she was told to make a separate payment to AIB for this month’s mortgage and was assured by an AIB staff member that direct debits will continue “seamlessly” next month.
AIB admitted that what it described as a small number of former Ulster Bank customers had had their mortgage direct debits cancelled this month.
It is understood the issue affects only a couple of dozen customers, but it is still an embarrassment for the bank coming so soon after the previous blunder.
“We are aware of a small number of customers whose direct debits were cancelled when their accounts moved to AIB following our purchase of Ulster Bank tracker mortgages.
“We are contacting any customers who had a direct debit cancelled to confirm we are working to resolve this error.”
AIB said it would now have alternative mortgage repayment methods in place for these customers.
“We want to assure our customers there will be no customer detriment and no credit rating impact where customers mortgage repayment is temporarily delayed due to our error.
“We apologise to our customers for any concern this issue has caused.”
Earlier this month, AIB had mistakenly told the mortgage customers – who were on tracker loans that were sold to AIB when Ulster Bank exited the market – that they were paying too little, leaving them facing huge increases in their monthly costs.
However, in an updated statement, on foot of revelations in the Irish Independent, AIB apologised to customers and said it would now “take all corrective action necessary to resolve the issue”.
The bank said it had made a mistake and there would be no increased payments, in contrast to letters sent to some customers.