The balance disappeared when Hop cards were topped up online but not used within 60 days.
Customers were still able to use the expired balance but had to call the company to have the money re-instated on their cards.
In September Phil Goff raised concerns with Auckland Transport over the bug. A number of measures were agreed to solve the issue including a warning on line telling people they needed to tag on within 60 days, automatic refunds and the introduction of a credit card or mobile phone system to tag on and off public transport.
Since May last year and April this year, up to $342,000 worth of transactions have been sitting with Auckland Transport at some point, including money that was reinstated.
Money on Hop cards becomes invalid if the card remains unused for six years.