It said it had identified that some customers with multiple banking products did not receive the correct discount on their Access transactions account.
"This review identified a discrepancy in the way their fee waiver was calculated and applied," a spokesman said.
"We prioritised resources to determine the extent customers were impacted and address the problem."
Affected customers were now being told that they would receive a portion of the $5.7m refund, which included a compensation component to recognise account interest that would have accrued during the relevant period.
Source:
BBC