But Dave if it was sent with a required signature on delivery then even in Australia they would rule you must have that signature or it would be a INR and nothing the seller could do as that was the way the postage had been paid for. The seller may argue your point about Proof Of Postage but the buyer could also argue that they paid for a Proof of Delivery by having to sign on delivery.

Still this doesnt help the OP. As people have said it may be that the site they bought off required Proof of Delivery and personnally I think ebay should also make that rule here in Australia. Think of how many INR claims that would stop.