They no longer just simply transfer to your new passport, that was changed in 2013, I got my new Marriage extension in July and PP runs out in Jan 23, (new one already applied for) I was told by immigration I have to make a new application all over again, 1900b. + a small forest of copys AND new photos.
With the OZ passport if the new one is posted to you and you don't collect it, then they cancel your passport there and then, which you keep, hopefully my new one will turn up before my 90 days is due, if not then worst case scenario, i hope would be a 2k fine, cheaper for me than going to BKK.