HRoth - 11:56 am on Jan 30, 2010 (gmt 0) It helps if you're a New Yorker with this technique.
Maybe you should reiterate the chain of events to him, pointing out without saying it out loud that he is being an ingrate. Something like, "You asked for something free (or discounted). I said I didn't do that. You asked and asked. Finally I felt sorry for you and sent it to you, something I would not normally do. Now you complain and say I sent you a piece of crap. What does that sound like to you?"
It helps if you're a New Yorker with this technique.