This may seem like a stupid question, but have you checked with the post office where you sent the item from?

It may have been a mere oversight on their part and it could still be sitting out back somewhere.

I'm talking from first hand experience as I posted an item a few yrs ago to Melbourne (from Sydney) and after 3 weeks it still had not arrived, so I checked with my local post office (where I sent it from) and they had a dig around and found it lying out back buried underneath other stuff.