I don't have a mobile data plan. We're waiting for my parents' contract to be up until we get a family plan. Anyways, mobile data keeps turning itself on for some reason and then AT&T keeps charging us $40 each month. And it's really annoying, as we're not rich (we got this phone off a family friend). Is there a way I could disable/keep it from being turned on any under circumstance unless I (the user) turn it on myself?