How do I disable my Dad's throttling epidemic?

I have a commercial level Luxul system, but my Dad capitalizes on the bandwidth even though he doesnt use it. Some rooms are told to specifically dial down to a lower frequency band (2.4ghz) to get better speeds only in the places they need it. Everything is hard wired that can be. It's unnecessary completely, and he currently also has it set up to tell 2 of 3 the ssid's to kick sand when he uses his own. The bandwidth is so much, he wouldn't notice it. How can I help myself? I only care because streaming music (even if the smart device is hard wired) will still require about 50 to 20 mbps. It tanks my bandwidth from 50 to about 5 in seconds everytime.