Why is my mobile hotspot so much slower than my regular data connection?

I always had fast tether speeds on a military plan, but this year it will to under 1mbps. Even the phone data would be about the same. every week id call and be told different excuses from different people. one guy said a previous guy removed my high speed tether and that he put it back. Then another said it had not been put back. I was paying $25 extra just for my line and for years it worked great in every state while travelling.  They say its tower upgrades, then the next person says its fiber optics, towers are down, towers are fine. they then convinced me to do magenta and it would only cost $30 more for the entire bill. i had them do that in hopes it would fix a problem that never happened before. i tried different phones and laptops so i know its not on my side. Anyhow, the bill jumped for each line. so we pulled the plug on Magenta due to lies and the fact the service did not improve. Im down to the 40gb that comes with the basic plan and in over a week i have not had to call and complain yet? we will see what happens when i hit the 40gb, but i decided instead of getting nowhere with tmobile ill just get cable internet. and, no i will not recommend tmobile 100%, because their reps lie and never fixed my problems. If your tech reps and such are so poorly trained thet you need to address this and your congested towers! I believe everything gets throttled no matter your plan when towers are congested! so there is no fix for your data problems...so dont keep paying them for add ones for bad service. i can get cable internet for $30/month...i don't need t mobiles lies!