"It is important that everyone who wants to take part in the action gets the opportunity to do so.
Hooker said there could be tens or hundreds of thousands of Kiwis still eligible to join the case.
"We will be doing what we can over the next seven weeks to ensure that as many people as possible know about their legal rights to join the case."
The case alleges that default fees charged by the bank in situations such as unarranged overdrafts, bounced cheques and late and over limit credit card fees are "unenforceable penalties" and should be paid back to customers.
Hooker said the case had also been allowed to continue as a whole rather than being broken into six groups covering the different fees as the ANZ bank had requested.
"The reason that an unarranged overdraft fee on a deposit account is unfair is the same reason that a credit card late payment fee is unfair - these fees are set far above what it actually costs the bank to manage the default that arises."
The next administrative hearing is expected to take place on 28 November 2013. A court date for the trial is expected to be set early next year.