negative feddback left without any reason

[pioneersounds]

here some buyers are tend to enter negative feedback without any reason.they do it for joy but it affects sellers sell very much. how to tackle these people.

[viztrends]

eBay should give option to seller to give -ve feedback for buyers.

For
Buyers who won bidding and not ready to purchase it
Buyers doing time pass and wasting our valuable time

eBay is completely on buyers side and it is not thinking about seller.

[tmart]

contact ebay support for it