Usage increase

After months of stable monthly usage (400-700GB), we are all of a sudden surpassing our monthly usage allotment. 

We have changed anything during this time. In fact, I haven’t even done online gaming this month and our usage somehow doubled. 

Reading through these forums it’s apparent this is becoming a pattern. I suspect it’s a scam to get people upgraded to unlimited internet plan. 

Why can we not get an answer on what is using up our data? It’s awfully convenient that you’re the arbiter and sole owner of the usage data, tell us it’s increasing, charge us for it, but can’t tell us why.