My usage is high. I have followed all the steps to reduce the need to use a large amount of data. I think someone is not following my rules :o(
The best way to see who, what and when data is being used is to get a third party router with traffic management or monitoring built in. I use an ASUS RT-AC3200 router. There are many other good routers available to do this. The Viasat built in routers have limited function, and a WiFi signal that is not nearly as strong as most third party routers.