UNFAIR EBAY NEGATIVE FEEDBACK! 1st negative feedback given

I am very annoyed with people.  I have done over 200 flawless transactions and am always willing to work with the customer.  However, this case was one that I did not appreciate.  So the buyer bought my item (borderlands 2) and it was in prestine condition and listed as like new.  I tested it before I sent it out.  The buyer played it for 2 weeks then stated that the game stopped working.  The buyer then demanded a full refund and an extra $5 so of course I am going to say no, but I did offer 1/3 of the original price because it wasnt my fault and they are the ones that messed with the game.  It is just unfair and they have no right to leave negative feedback