tmobile home internet speed issues

When I had the older modem, 4G. It was one for the testing areas. I had good internet no issues at all. It was great. Then they switched to the 5g modems. The gray ones that get warm. I hardly have anything now. I even have to tether off my phone at times., it's that slow. They sent me a replacement modem. Didn't change anything. T-Mobile has told me it's because there to many people using the towers. I said then you are throttling my internet usage then. T-Mobile said no they are not restricting my internet. I asked if there are too many people using the tower, who is getting service and who isn't. If I am not getting service, then I have to be throttled till a certain time because I can only use t mobile internet in the morning and later evening. During the day, forget it. And they dont care. Its put up with it or find a new internet provider.