You will not get the return shipping charges back. Those are the responsibility of the unhappy buyer. Some sellers will, for ethical reasons, refund return postage if they agree the error was theirs.
Some.
And it is not mandatory.
Seller agreed to refund, as long as I return the two cases. Seller was to pay for return shipping as per ebay listing.
The seller was undoubtedly shocked by the high cost of tracked return shipping, which I believe starts at $40. At least you got your original payment back. That's as much as Paypal and/or eBay would refund.
You have 60 days to leave feedback from date of purchase.
You will be asked at the same time to leave Detailed Seller Ratings about your transaction. A normal, nothing special transaction gets Five Stars. The lowest rating is ONE STAR. If a seller's DSRs drop below 4.3, his selling account will be restricted in several ways.