Instead of -ve Feedback where by you will gain nothing,except a Pyrrhic Victory, which is in business sense useless, Open up eBay guarantee claim and item not as described case and return back the headset for full refunds.
Why you want to get personal with your seller or eBay follow rules and procedures and firstly if you buy from some one do a research on that particular product by checking his feedback and also past user experiences , same as you do in offline market, why all of a sudden you forget the norms of off-line market once you come on-line.
The rules, sellers and market place is safe, difference is its much simpler and faster on-line and you got a heavy weight referee here , who i vouch by is 100 percent JUST and Wise in form of eBay, you just have to knock the right Doors.
Take the path of -ve feedback only when seller is totally obnoxious, but 99.9 percent times ebay sellers will be not, as there are lot of checks and balances in place, And yes Check the DSR ratings too, the entire eBay market place is quantified in terms of numbers, which is easier to gauge and understand for a customer before buying anything. No where on any portal in India or even in off-line market you will get such a HUGE variety, plethora of information, the safety of your money and also the luxury which eBay gives to Buyers.
Just ask the right questions for right answers, then the doors will open, trust it my friend , as days pass by you will learn the art of eBaying.And will get addicted to this Market place.