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This.
Also what has been said about not having him collect it or even making that an option.
Also if the original packaging was damaged at all in transit(?) grab an old wooden pallet and place the bike box on that then explain it's being shipped by pallet in the hope the goods aren't further damaged. As a downside to this shipping a pallet is far more expensive for the other guy but I think what we all want here is the goods to arrive back safely.
Don't relinquish the frame until the PayPal claim is finalised.