Thousands of bank customers across Australia could be unnecessarily out of pocket hundreds of dollars, unaware of changes made to a popular banking account.

ANZ bank customers wrongly charged a monthly transaction fee are being reimbursed hundreds of dollars. Credit:Henry Zwartz

ANZ customers with an Access Advantage account could be incorrectly getting slugged $5 each month, despite the national bank abolishing the fee five years ago, subject to conditions.

Access account holders were charged the monthly servicing fee, equating to $60 a year, before ANZ scrapped it in 2013 for customers who fit certain criteria.

Customers exempt from the charge had to have opened their account on or after November 30, 2013 and deposit at least $2000 by the last business day of each month.