Internet speeds slow way down mostly at night

For the last 3 months. I have been having severe internet problems. Anywhere from around 9pm. Really bad after midnight. I pay for 300 down 30 up. At times my internet speed will drop to under 1. Its been as low as .02mbps (have screenshots). Now that test was ran wirelessly. It may make a difference but not that significant. Also whatever is connected to the modem/router combo with a cat 6 cable stuffers the same fate. I have had a technician out here multiple times. I think 5 or 6 times. Everything is fine. I switched the modems. Same problem. Called. Tech came here changed some fittings. Didnt fix my issue and charge me a professional installation fee. When I am having the internet speed problem. There are no techs to come out. It's too late. I work at night so I'm up at night. They have told me they are sending my problem higher up. But haven't heard anything from it. Everytime I call. Its "Its let me ping your modem... I cant locate your modem. I'm gonna send a tech out." Tech gets here. "I dont know man. Everything is fine on my end." Which isnt their fault. They showed me the tests everything was good. But the problem is getting worse. To the point where my internet is not useable at night. I'm paying quite a bit of money a month.