This has been a continual problem for months. I go into Data Usage and switch mobile data to "off," but it always ends up on again.
It used to turn back on instantly: turn it off, navigate away, come back, and it's on!
Then it would only sneakily turn itself back on after a while.
NOW what it's doing is it says it's off, but the little status icon shows that it's using mobile data!! What is going on??? NO means NO, right?? How can I stop Verizon from raping my data plan??