Can AT&T unlock an Iphone 5 for someone thats not on their network?

So i bought an Iphone 5 on Ebay and the description was "Factory Unlocked" but when i took it to
T-Mobile i found out it wasn't factory unlocked… So i'm wondering since the carrier in the phone says AT&T, can i take it in to a local AT&T store and get it unlocked? If not, could i unlock it myself? Or find someone who unlocks phones to do it for me?

Myphoneunlockcode does cheap unlocks, they take a while though AT&T might be able to do it, for a high price

AT&T will not unlock a phone if its on someone elses account and you do not have an account with them. But you can pay someone to unlock it

No. It is on someone else's account and not only that but I suspect they have outstanding payments which is why they sold it. So you are screwed.

An expensive mistake.

The only way is to order an unlocking through a third party like Keys2iPhone. But there's no guarantee it will be unlocked, especially if it was a subsidized on contract phone and the person who sold it to you still owes money to At&t.