I increased my data plan today and suddenly my phone appears to be using far more data than before with each use. Samsung note 2. very strange indeed. I try turning off all apps other than the one I want to access. Email Usually.
Take a look at the following. Sudden surges in data usually indicate some setting has been changed. Perhaps you were being frugal before and limiting yourself to wifi and now the mobile data tap is on full-blast.
I usually use mobile data only for checking email, not for downloading and streaming on my Note 2, and have a hard time using more than 80 megs a month by following this scenario: