I don't know what's going on with my data usage on my iPhone. I have only 200 MB of cellular data each month and usually I use only about two thirds of it. However, occasionally I have a month where I come a little bit closer using it all up.
Last month I got a note saying that I had used 90% of my data with two days left to go on the plan. So I shut down everything except for my email thinking that I wouldn't use much more data.
My phone continued to use data even when the cellular data was turned off. It even used 7 MB of data while I was sleeping in my apartment where we have Wi-Fi.
Wtf? How is that possible?