Weak signal at work

Over the last 6 months I have had horribly weak signal at work. In 85142 zip. I can barely get 2 bars sometimes and it is even weak in 4g. I never used to have this issue. I switched from Tmobile to Verizon to solve this issue and it was FAR superior for the first year. Now I feel like I should save money if I'm going to be paying for the same quality service I was getting.....