Hi @ocoach
It is often done ... but the seller needs evidence that the feedback is untrue and/or unfair.
Your Reply to the feedback proved the buyer's point, I'm afraid. It was in ALL-CAPS and accused the buyer of lying. It looks like something a 'rude' person would do.
Seller's Replies should ALWAYS sound calm and professional. It makes the BUYER look like the bad guy if buyer's comment is angry ... so the seller looks good even if eBay doesn't remove the FB.
