Unlocking iPhone 4s with ATT?

I bought an iPhone 4s off of ebay and it was supposedly unlocked. It came with the gevey sim, but it wasn't working with my tmobile sim card. I brought it in to apple, and they basically said to contact ATT to see if they would unlock it for me. Will I be eligible since I wasn't a former ATT customer and that i bought it off of ebay? The apple worker also told me that since it was still under applecare, they can swap it out for a new refurbished iPhone. Can they do that too, like just swap it out for no reason?

No you have to be a customer but you can WIRELESSLY PERMANENTLY FACTORY UNLOCK any AT&T iPhone at http://iswapple.com
it works for any iphone 3gs 4 4s 5 and any firmware. Plus once you do it you can also update when ever you want because its a factory unlock… Cheapest wireless unlock it was like for 20 bucks