General :: Galaxy S4 - Lock Or Password Protect Phone Settings Or Data Usage?

I'm on a family plan with my wife and 13yr old son. We purchased a Galaxy S4 for our son as a Birthday present in October. However, as of recent his grades have taken a dive. We notice he eats, sleeps and breathes on the phone. He primarily uses it for surfing the net, instagram or youtube. We were thinking of grounding him and removing his phone but we need him to have his phone as a point of contact. However, is there anyway to stop his data usage. I realize there is a setting on the phone to disable data usage but it is fairly easy to re-enable it.

Is there anyway to lock or password protect the phones settings or data usage?

I tried googling but the results kept yielding information relative to the "lock screen" which isnt what im looking for.