Same thing happened to me, i did receive a negative feedback on 24-May-2009,
I won the case at community court and they favored me, but the negative feedback is still present.
I did contact ebay customer care many times via online support as well as phone, they have no solution.
They are helpless and always tell to send a mail to inrswebhelp@ebay.com, or same email id like this, never got any revert from them.
eBay is earning money from sellers through listing as well as paisapay but they dont look after the issues of the sellers.
shame on ebay