Every night at peak hours internet speed is garbage.

I have been trying to fix this problem for over 4 months now.  I have had 4 techs to my house, I have exchanged modems 3 times, but the same nonsense is still going on.  As soon as peak hours arrive between 5 pm and 12 am my internet speed slows down so much I literally can't  do ***.  I have been told so many stories about saturated nodes and noise outside my house that could be causing the problem, but nothing has been fixed.  I can't stream anything, video game are filled with lag spikes and connection drops, and downloading anything at night just isn't even an option.  The connection is terrible with wireless as well as wired.  So if I am paying for something, but not getting what I am paying for, is Cox just stealing from me?  I have a security system through Cox that uses Wi-Fi and half the time the internet isn't working so therefore the security system isn't working. I started taking pictures every night of my internet speed. Maybe a lawsuit will fix the problem.

Someone fix this ** please.