If you follow the eBay Money Back Guarantee (MBG) procedure, yes you will receive a refund in full. The seller will either send you a return label or refund you in full, letting you keep the headphones as well.
To do so, use the drop down menu and click on "return this item" then follow the prompts from then. Do not let the seller stall you. Accept only a return label or a full refund) If they send a label, pack the headphones up and return then (using an on-line tracked method.) Upon arrival, I believe the seller has 48 hours or so to process a refund in full.
If you do not hear from the seller once you enact the "return this item", within x days (2? 3? 4? 5?) you can ask eBay to step in. This will not bode well for the seller as usually, once eBay steps in, the buyer keeps the item and gets a refund in full.