The following issues apply only to Residential Sales Agencies
Essentially better practice is to use a Subsequent Agency and not use the complex Extension rules under the Act.
A Subsequent Agency should be done prior to the Agency expiring and not used when an Auction Agency is in place.
The Act states only 1 extension is allowed so if done afterwards it would be a new Agency Agreement that is used. To tie back in before the Agency lapses use the Subsequent Agency form in the Society of Auctioneers form (reaforms.com.au)