I know this is an old post but I'm in the same situation.

Who pays for the postage?

The item I sent never got scanned, should have been delivered almost a week ago and now I am out the item, will be refunding the money and just recieved the bill for the postage and seller fees. 

Is this all a loss to me? I have opened a lost parcel case with Australia Post, so just wondering whilst I wait to hear back from them