How is cox able to prove you are actually going over your data usage?

I have asked for details of my so called overages, to understand what is supposedly consuming data in my household. They cannot provide any details. How can you claim I am over my usage if you can't provide details of that so called use. What a farse.  Cash grab by greedy company losing cable subscribers so you had to make up some fake way to get more cash out of non cable subscribers. Provide details, or stop making up fake numbers of our so called usage.