Constant unwanted automatic data refills I didn't opt in for and can't switch off,data disappearing it hasn't been switch on

I keep getting R3 taken off of my airtime for a 10mb data refill that I haven't opted in for,there is no way to switch it off,I have tried *135*6#. I haven't left the house in days,I have been using only my wifi without mobile data being switched on and yet data is disappearing and being refilled automatically. My phone show no mobile data as having been used. How does this happen? I feel like I am being ****** here.