Refund finally processed the other day. Kelley at i-Parcel was great help - apparently not only did mine ship, it was delivered, without signature, and likely nicked off the door step. AusPost couldn't confirm anything as the contractor no longer works for them.
I'm just glad to have the whole thing behind me.
As for TRU, they were useless. I just placed an order for the SDCC movie Turtles (not available for international shipping) and am having them dropshipped.

No i-Parcel, no international lack-of-assistance from TRU, and probably a whopping shipping charge from MyUS.