Need help badly. cannot get receipt

A few days ago, I updated my iPhone to iOS8 and I got stuck on activation lock and my iCloud account was locked. I took it to the Apple Store and they said they could remove it with proof of purchase or a receipt. I had since lost the receipt since I bought this phone almost two years ago.

The AT&T store I bought my phone at had closed down so I simply went to another AT&T store. The service was rude. They said I cannot get my receipt since I did not buy the phone at that store and the store I bought it was "wasn't corperate" so they had no records of it. I then went home and had an online live chat with someone on the AT&T website. They said they had record that I bought my phone but no invoice. They also said I cannot get my proof of purchase except where I bought my phone. She then cut my chat off before I could ask anything else.

If it closed down, where am I suppossed to get it? Where is all the infromation I gave that store? 

This is extremely frustrating and I am now debating on if to ever get an Apple product again and if I should stay with AT&T anymore.