The AB139 that HNZ have on order has been delayed because they dont have a contract for it from what I heard.
Also yes they are the only operator in NZ that is currently doing offshore.
In OZ, as far as I know there is Bristows, CHC, Esso, Jayrow and a couple of single pilot VFR machines in Western Australia.
Others here based in OZ might be able to elaborate further.
Cheers
Ned