Australasian lender Westpac has been fined NZ$570,000 by the New Zealand Commerce Commission for overcharging customers on international credit and debit card transactions.

Westpac has become the fourth bank to plead guilty to the charge of engaging in unfair practice and breaking the Fair Trading Act. The lender will also pay back NZ$4.5 million in compensation to customers, taking the total for agreed compensation from those that have pleaded guilty to date to the NZ$20 million mark.

However, the Commission has in fact brought charges against 10 firms in total. In addition to Westpac, Kiwibank has been charged and BNZ has been fined NZ$550,000, while agreeing to pay NZ$5 million in compensation.

While issuing a fine, the Commerce Commission urged lenders to focus on maintaining adherence to protocols and not each others’ practices. The statement follows defense suggestions that banks were simply falling in line with each other when determining international transaction fees.

In all, Westpac pleaded guilty to 19 counts of breaking the Fair Trading Act.