Phone manually resetting through encrypted texts


Hello all,
Brand new to androidforums, but really, I am out of options.
A few weeks ago my old phone started acting up, factory resetting itself every 1-2ish days. I thought, heck, its an old phone, and I need a new one anyways, so ill go get a new one to get rid of the issues. I get home with a brand new phone, from the T-mobile store; set it up. Less than a day later the phone again, is factory reset. At that point I called tech support, which tried to see what in the world could possibly be causing this and came to the conclusion that it was a phone defect and that it all was a terrible coincidence. I go to t-mobile & pick up 2nd brand new phone. I changed my google account password since that was the one thing being transferred between phones just for safety. That was yesterday. This morning, the phone was still working fine, and as I was typing a text to a friend I happened to be at the phone at just the right moment; I get an encrypted message from a number with my local area code; says something along the lines of "forceandroidreset558465:"..and phone reset itself about 15 seconds later. So at that point it is clear that SOMEONE is doing this. Basically, I need to know how this is happening, and how I can stop it. Do I need a new Google account? Or is this phone # related? how could anyone possible be controlling a brand new, no new apps installed, out of the box phone?
Thank you for the input!!