Hi all, I have a scenerio, I sold an iPhone 4 on amazon in the end of september, it was in excellent condition worked perfectly fine. I shipped it to the guy, he got it within 2 days. Now 2 days ago i get an email that he wants a refund because the microphone isnt working (people can't hear him). I never had any issues with the phone and I am 100% sure that it is working perfectly fine. I sent the guy an e-mail back asking him a few questions about possibly people can't hear him as well because of his carrier or the location where he talks on the phone or w.e. He never responded to my e-mail as of yet. What should I do??