I have no idea what you mean by an 801 radio frequency, and "push to talk" was a technology we never had over here. But I doubt you could manage an internet connection through it, and it's an internet connection that's your main weakness (unless someone has installed something similar to some anti-theft products which allow you to turn data on remotely via a binary SMS - in that case you'll need to put it into airplane mode to stop it).
Getting the GMail account out of their hands is the top priority. If you can't reset that via a browser on your phone you need to borrow another internet connection for a few minutes to change that. A quick web search pulled up
this page of suggestions for what to do if your account is hacked, but obviously it would be better to follow such things from a device which isn't already compromised like your phone is.