File a complaint with FCC
It is a common practice with t-mobile with false advertisement and promises. Where they claim they have LTE, they actually have bare 2G speed. I had tried them twice in two years and cancelled within 3 days both times.
I guess you should file a complaint with FCC regarding your problems with t-mobile. Include/attach any correspondence you have done with t-mobile in this regard. Believe me, they will act on your behalf and you will hear from t-mobile/FCC typically in 3-4 weeks time.
No wireless service can provide good service to everyone on earth no matter where they might be. Unless they are using satellites they would have to cover the whole world with towers just a mile apart to insure a strong signal everywhere and even if they had the $billions to do that it would be physically impossible. Also they are not allowed to put towers in many areas due to zoning or because the area is already built up. It might just be his HOA or city or county zoning not allowing it, why not complain to them?
Or better yet, if it doesn't work in the area switch to a different service that does. No more whining or FCC complaining necessary.