24-08-2016 9:03 PM
The buyer can only pay what eBay invoice them. The eBay invoice will include the cost of shipping (Pitney Bowes' charges) from the UK hub to the buyer, you get the domestic postage (delivery to the UK hub) and the item value. You cannot refund the Pitney Bowes element of the transaction because it doesn't go anywhere near your account.
In short, you are correct.