Unhappy [Q] Issues with calls and texts after 4.3 update

I have a T-Mobile Xperia Z 6606, when the 4.3 update originally rolled out I promptly update, once I updated everything was fine until I went to work. Once I got to work I found out that I could not send or receive text messages nor could I make or receive a phone call. If I rebooted the phone I would have a small window of time that I could call out, or receive texts that had been sent earlier and I never got, or send a quick text out, but after a minute or so it would stop working again.

Now I have never had great data reception inside my work building but I never had troubles with calls or texts until the 4.3 update. I would also keep getting a notification that I needed to sign in to the T-Mobile network, and the 'H' by my signal bars says H+ on the 4.3 update, prior it was only ever an H, and it sucks my battery dry. After a 12 hour day I would typically have 25-30% battery but with the connection issues my phone dies around the 10 hour mark.

To attempt to fix the issue I download an unbranded 4.2 rom and installed it on my phone, and after that my phone went back to working as normal with no issues. I was consistently getting update notifications to update OTA to 4.3 so last night I decided to give it a go and finally update to 4.3 once more hoping maybe it was the T-Mobile rom that had an issue, but no go. Even the OTA non branded rom has the same issue.

Does 4.3 use a different radio than 4.2? Is it possible to use a 4.2 radio on 4.3?

I love the 4.3 version as it make my phone run so much better, but I cant use it when my phone is useless at work. Anybody have any ideas what could cause this or how to fix it?