Today I received a negative feedback from a buyer, after over 1240 feedbacks for 100% positive reputation.

The buyer bought something that is a spare part of a larger set.

Upon receiving it, buyer demanded that I send him the full set.

Naturally I refused, but I offered him refund if he return the item to me.

He then threatened me with negative, and  now after I maintain that refund will be given if the item is returned, 

He posted a negative feedback and claim for goods not as described.

Simply looking at the feedback he gave to other sellers you can see that this buyer is a liar and a predator that regularly use this trick to obtain goods.

I have sent an email to ebay reporting this extortion, but I wonder if ebay would do anything about it.