Originally Posted by Mos6502

Actually if a buyer is reporting an unusual number of sellers (ie. they keep opening cases for refunds) ebay will investigate - and they may suspend the buyer's account. Of course they have to be a serial offender before this happens, if it's just some jerk who randomly decides "hey I want to keep this" one time - good luck. Also if a buyer is trying to extort a seller by saying they will leave this or that feedback depending on what you do to appease them you can report them and they may get their account suspended. But they have to literally be making that threat, not simply implying it.