That sux mate.
I'm kind of in a similar boat. Few things ordered for the car left NSW on the 18th of this month according to tracking and are still listed as "Received by Australia Post" at the original post point. I lodged a claim/inquiry about it with auspost, and all they could tell me is "Oh it shows us that it's been submitted at such and such on the 18th."
Like no s#it ??? I can see that my self on the tracking page. And supposedly nothing more they could do.
As of this morning, the sender or auspost have no clue where the package is. It's also registered and sender did pay insurance but it's very frustrating ...