Default [Q] Network Unlock

I've had my Cap Glide for about a year now and when I got it, I called AT&T and got an unlock code, so I could use it on T-Mobile. A few days ago, something happened and the phone was asking for an unlock code again. I called AT&T to get another code, but they don't do it over the phone anymore. Now it's done through their "unlock portal" website, which denied me twice to get another code.

I have looked through through XDA for ways to unlock it on my own, but without much success. Does anyone know of a way for me to unlock the phone simply for network use? The phone is not rooted or modified in any way.

Any help is greatly appreciated.