I'll set this guy out, he's got some more negative feedback since I left my neutral. For not shipping items
Did you actually look? We are sitting here 9August and three negz are ".never sent" for items due to be delivered NEXT week, 14-18August. The other one is eBay refunded over sales tax issue (which is on eBay) although "seller never responded" is a concern.
There is a way to send a message to the seller that you can tell him what a bum he is. It would probably be erased as well.
Do you want to possibly buy from this seller again? If not, negative feedback all the way. Otherwise, maybe there is a good explanation, if so, what to do next is up to you.
That is the best way of handling crooked sellers who cancel or claim they lost coin. And then re-list the same coin later. I also look at their feedbacks and if I see they have a pattern of "losing" coins, I will call eBay and file a complaint against the seller.