creamerybutter

I have a slight problem:

I sold a mobile phone at the end of may, it was damaged but it was only cosmetic and was fully detailed in the auction (with detailed pictures). I tested the phone literally 5mins before I boxed it up and it worked fine.

Anyway the buyer bought it and left me positive feedback and now nearly two week done the line they have messaged me to tell me it doesn't work.

Obviously I want to help them as much as I can but I was wondering officially what do I have to do? Will I have to take back a phone that was working when I sent it? Will I have to refund them fully?

I have tried contacting paypal/eBay but they don't seem to be to quick getting back to me. Just wondering if anyone here has any experiance with this kind of issue?