Sounds to me this is a matter for the sending courier, if delivery can not be proved then the parcel insurance needs to be claimed.
judging by the parcel number it was not sent on a priority service, in my experience (about 8-9 years worth investigating lost parcels) it is not unusual for items to take 2-3 months in some cases to that part of the world to turn up, I am unsure why, delays, custom delays sometimes they turn up at the delivery address, other times it gets turned back and returned to sender all of which can take months, item getting lost.
Oh and in addition don't not be surprised if both sending and delivery courier blame each other, tell them to drop the bull**** and sort it out. Sending courier should compensate the sender if the delivery is lost, and if NZ post lost it they will compensate the sending courier.