Factory unlock iPhone requires receipt but I don't have one?

I called AT&T and they require a faxed receipt sent to them. What to do since I bought phone off e-bay and do not have an AT&T receipt or Apple store receipt. I also tried going through website and it also requires the receipt. How can I get around this? I see all over the web people charge $15-$50 for this service. How do they do it without receipt?

I know there are some official apple unlockers like who unlocked my friend iPhone.
he bought an iPhone and used a website that offer remote unlock.their unlock was official apple unlock and done through apple. I think the price was $25 and the iPhone unlocked in 12 hours. They just got my friend iPhone imei # and unlocked it.
check their website:
http://officialappleunlocker.com/