Poor premium Internet +customer service

I purchased a 2 year 50gb LTE Advanced modem which is supposed to give me between 50gb and 150gb down load speed. First month service was great... Then just plane bad service. Brand new Tower is a stone throw away and I just can't stream my movies anymore. Come 7pm Telkom switch something over and internet is even worse. Like clock work every day at 7. I do a speed scan and the line say between 8mb and 20mb yet I still can't stream. This is not quality of service. I laid a complaint which took me 1hr in store and 2months later I have yet to for someone to contact me. I have purchased a booster but that still doesn't help. I want a solution to why your network caps at 7pm.why I have poor streaming speed on the fastest modem u can buy... Oh yes and I am in the LTE band range so u can't tell me any different.