The Consumers' Association has said AIB's response to the overcharging of customers indicates there is no change in the culture at the bank.
The association has also accused AIB of having a lack of understanding about the consumer position.
The Irish Financial Services Regulatory Authority said today that the bank would refund almost €35 million to thousands of customers it overcharged.
The results of an independent investigation into foreign exchange and other overcharging by AIB were published this morning.
It is the first of three inquiries into activities at the country's biggest bank following recent scandal revelations.
The report details the amount overcharged, the number of customers affected and how the bank is returning the cash.
IFSRA Chief Executive Liam O'Reilly said AIB had failed in a number of respects.
He said that in some instances, the bank charged customers more than it was entitled to and failed to notify the regulator - as required by law - in relation to certain charges it levied on customers.
The statement confirms that the number of affected foreign exchange transactions is estimated to be around three million.
Overcharging exposed by RTÉ
The investigation was set up in May under the approval of IFSRA after an RTÉ report exposed the overcharging.
Today's report follows an inquiry led by former Comptroller and Auditor General Lauri McDonnell.
Two further reports will examine why customers were overcharged and how this went undetected for almost ten years. The final report will focus on AIB's internal systems and controls.
AIB originally estimated that the amount overcharged was €14 million but later lodged €25 million at the Central Bank to compensate those affected.
AIB apologises
Meanwhile, AIB has once again apologised to its customers and confirmed its commitment to fair and honest dealings at all times.
It also confirmed that it would make every effort to repay customers who had been overcharged.
The bank is to commission an annual independent audit of fees and charges for a sample of customers and will report the results to the regulator.
