Horrible Service Durring Peak HRS

I have had horrible service ever since i moved into my home, where I have a home business, last November . I started out with extreme 105mbps on residential. The internet service would fly durring the week days in the morning and afternoon I would get 120+ Mbps. However, as soon as 4:oclock hits it will start to crawl. By dinner time i  only get 20mbps. I switched to buisiness in hopes i would have better QOS and the issue would be fixed. It is not fixed! It is horrible durring the nights and the entire day on the weekends. I am only getting around 9mbps now, but I am paing for 75 on Comcast buisiness.

I have had 10 techs out and have been told my signal is fantastic and nothing else. Its almost like they dont care. This has to be a congestion issue. What do i do?