I've only been 'burned' 2x in an eBay purchase, but I waited until the date of receipt had passed before opening a case. One item of two from the same seller from China never arrived, when I queried the seller after the delivery date had expired he immediately refunded my money, which was very nice of him because he 'ate' the loss. I gave him good feedback despite not having an item and waiting 1 month.
The second seller was from a USA source. He never returned my emails, item never shipped. eBay immediately refunded my money without question.
In legal issues in the USA, you send 3 polite demand letters, return receipt. I did the same via eBay mail, about 1-2 days apart; eBay can get copies of those communiques from their servers, so you need not CC it to someone. The day my delivery date expired and I got no reply from 3 emails, I opened a case, and in a few hours, I got the money refunded and judgment to me. The seller's ID disappeared a few days later, too.