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

I was a huge fan of TMobile up untill 4 months ago. I would tell everyone " I'm never going to cheat on them"I really loved the customer support. As of recently I want nothing to do with these people they are scamming us. I have been through so much with not getting sufficient speeds to be able to work. I upgraded my plan, I bought a new devise, the new devise didn't work, I had to be at the store 4 hours when I was supposed to be working. They lost my sim card to my phone and the connector. When I tried to tell them the new phone won't even connect they tried to tell me it's promotional I can't return it. I said but it doesn't connect. Wtf do you mean they told me well does it make calls? SMH really TMobile. Finely I told them I'm not leaving untill they return it,I sat there plugged in my work computer. They finally said they will return it. After that They upgraded my plan so I could get "better signal" knowing the towers are down. They then said oh we can rest your Internet it should work better. And that didn't work .. meanwhile I'm spending hours in between on the phone with reps and in store. Finally I get my people at work to test my speeds, or lack thereof. I let them know I'm about to loose my job due to this it's making me look like I'm playing around at home and not working. I let them know the speeds and that was when I found out about the "towers are down in my zip code" these people then apologize and offer a $30 credit. I say thank you but what I really want is a working connection. They then offer to reset phone again. The service was worse. Now I need to pay for childcare go into the office and work. Now we are on month 2 of issues I attempt to work from home.. same thing but I can't even connect at all. I call them they say wouldn't tell me about the outage in my area so I let them know, they. To my surprise yes man it's been out for several months but they are working on it. The last guy did not not give me my credit I told the lady that I was promised a credit and was not honored and she said my personal guarantee. He will credit the 39 and what I'm going to do for you is give you another credit of .....I  said I just want working internet.  Well I ended up getting a $25 credit and that was all. I called them I said you guys promised 2 credits and all that's there is 1 for $25 and that's after I complained about it not being there. They said well we can't refund you any money that was a promotion. Now my blood pressure is through the roof I have my boss texting me wondering what's going on, ... The stress these people cause by trying to give you the run around is BS. They just care about the next $1. Well I let them know they are crooked taking people money for upgrades and selling new devised and mo to