High data usage

In early December I ditched DirecTV and decided to stream live TV (PlayStation Vue through Roku) using Cox's Preferred 100 data plan, mainly in order to reduce the $160/month I was paying for DirecTV.  All was well the first month of streaming, but about halfway through the second month I was notified I had used  more than 1TB of data.

This baffled me because our usage was hardly any different the first half of January than it was all of December.  We stream live TV on two TVs (no movies, no gaming) and also have an iPad and two iPhones that we occasionally use for email and internet.  These are the only devices we have that would consume any data (that I'm aware of).  Our usage went from about 30-40 gb per day to more than 100.  I changed the wireless password and usage dropped back into the 30s, but this month it is regularly at 70 or more per day.  And yesterday, when I was away from home and one TV was in use for no more than three hours, my data usage was 91gb.

Am I missing something?  Is something constantly running even though the TVs are turned off that is burning so much data?

Appreciate any feedback.