Why is my mobile data

[Android Central Question]

My phone is galaxy j7....my daily mobile data offer is 1.4gb...when i go to sleep I turn off my mobile data...usually when I wake up and check my mobile data...it is used usually the balance is 400mb...500mb..etc left....why is the mobile data using even if the mobile data is off?

 

[B. Diddy]

Welcome to Android Central! Sorry for the basic question, but just to be sure -- you're turning off mobile data, and not wi-fi, right? Are you going into the Settings>Mobile Networks​ menu to turn off mobile data, or is there a Quick Setting?