I Have A Bone To Pick With Ebay!

I know what your thinking....join the club!
I'm assuming nearly everyone who reads this post has had an ebay experience or multiple for that matter which makes you think....screw ebay or to the extreme "never again will I do business on the ebay platform".

I have bought more coins on ebay than ive sold but recently I've been selling a few coins and they will were listed as buy it now with a best offer option. I had some Daniel Carr Tokens with 100% feedback.
A buyer made an offer on one of my tokens and I excepted tbe offer. Shipped the token and since everything went perfect I gave the buyer 5 stars perfect buyer would do business with again and a thank you. Only to find 2 weeks later my feedback score went from 100% to 80% because this buyer said ..." High, Pricing" and submitted negative feedback...not even neutral.
huh.....they submitted an offer to me which was lower than the price I had listed and I said ok and everything was fine except for me taking a cheaper price and this person has the audacity to then submit negative feedback saying high pricing.
I've reached out to the buyer, tried to get this taken down talking to ebay reps, the buyer won't respond , would do a return no problem and pay for tbe return shipping. I think this is fraud. Seems like another seller trying to screw me?
Has anyone ever had something similar happen to them like this?
I would be appreciative in reading the community's opinions of their negative experiences on ebay (especially if their is advice on how to remove unnecessary negative feedback from unscrupulous buyers/sellers.)