Aww you poor thing . Unfortunately there is not much more you can do.

Did you lodge an investigation with Australia Post? They can chase up missing parcels for you (even if they're not registered). They only refund up to $50 though for non-registered parcels .

I had a parcel go missing last month, after much chasing up I ended up refunding the customer. The parcel then turned up 1 month late . Luckily the customer sent it back so neither of us were out of pocket in the end.