HTC Windows 8 (8X) Verizon startup screen & issues on a T-Mobile network

[WPCentral Question]

So for the last few days I've been trying to learn/figure this out, and I've had no luck. My wife and I purchased two HTC Windows 8 phones that were supposed to be unlocked (through Amazon). Mine works fine without any hitches (I absolutely love it) Her's on the other hand has been nothing but trouble. Here are the problems we are experiencing. We can be sitting right next to each other and she is always on extended network or at best 3G where I will be showing 4G. Her text messages don't send out. Randomly it shows it is on "H" network (couldn't figure that one out either). We have contacted t-mobile several times and they can't seem to find anything wrong on their end. We have switched sim cards and the problem stays on her phone. We've only had the phones a little over a week, but I've found it odd that her startup screen is a Verizion screen even though we are on a T-mobile network. They have had us try to manually setup APN settings, but it does the same thing (staying on extended network and not willing to send texts). It also lacks a lot of options in settings that my phone allows for. I just don't know enough about these phones to have a clue as to what is going on. Is it a bad phone or a bad user? Any help or information would be greatly appreciated.

 

[switch side method]

Go to settings

Cellular+sim

Sim settings

Make sure 4G is clicked. Let me know if it works