I've just used this for the first time, and it will be the last as the extra charges were horrendous.
The actual eBay order receipt shows the item price and then the customs charge, and the PP receipt is split into two payments – one to the seller (item cost) and one Pitney Bowes, (import charge and postage charge).
Is this a return for repair/replacement? I take it there isn't an online form to indicate charges have been paid? Have you asked eBay?