At renewal time your data resets. So when you log into your account right now you see all the data being used? Under my data and add-ons. Or you just got a text notification? I ask as sometimes a data usage text is sent in error.
You mentioned something about tablet. So do you use your cell phone as a hotspot sometimes for your tablet? You'd have to go through all settings on both devices and make sure they're set correctly so data is on a Strick ship. One software update can easily use a few gigs. Do you use it to hotspot other devices as well that may have come near the connection?
You want to set your devices to update on on wifi.
Now yes you may always use wifi BUT you have to fix those settings to. You need to turn off wifi assist or wifi + that automatically switch back and forth between wifi / data if the wifi signal is weak or having issues. So streaming something and your phone notices your wifi is acting up,etc it automatically switches you back to data for a better connection.
You should also look in developer options for "mobile data always on" some devices have that setting.
Then of course go through each app to set them correctly on what can run only on data and what can only use wifi. Then restrict background data also.
You can log into your account and click "view usage" under "change plan" and go through each page. It will show each date and time data was accessed and how much. (Eastern time) you're looking for "Data Event" Web.
You can also go in your phone settings or tablet settings and view your data usage there by day, week, month. It will even show what apps used the most data.
Keep us posted.
