And there is little you can do
I had a case with UPS full traceable and expressed shipping. Signed for receipt with clear name and details. So I could prove I had delivered the goods and they were received at his address. I followed all the rules paypal say.
No luck they charged back and paypal wash their hands in innocence saying they can't do anything about it. Money gone, goods gone.
Sometimes paypal sucks. These are a few of those cases.
Alas. good luck to your case, Hans.