I have been selling on ebay for years and recently I notice buyers are leaving negative feedback or bad rating without contacting me for any issue(just received a neg. feedback today and the buyer never contact me for any problem).  In the past, I usually contact the buyer first but they either not reply my emails or refuse to resolve the issue.  What can sellers do?  I don't think the feedback system is showng the true seller performance but nothing we could do.  Ebay never listen to sellers.