I recently sold a wireless headset on craigslist. The item had never been used, was still in original box with all plastic wrapping sealed and was advertised as such. Later that night the man who purchased it called me and claimed it was defective... he asked for the receipt, which of course I do not have or I would have just returned the item to the store for the full amount paid. He is now asking for a refund. My issue is this, he is the first person to have taken it out of the plastic, so if it is indeed defective than I would not have known that when I sold it to him. Secondly, how do I know he did not replace a broken one with the one I sold him and is claiming the one I sold doesn't work... and lastly, I already spent the money and really don't have it to give to him. Now he is blowing up my phone and I'm not sure what my obligation is.