Hey landslide,
When I was younger, I had a problem with abusing smartphone privileges similar to your d. It was very concerning to my parents and believe me, I now feel so bad about everything I put them through.
How they handled it was very smart and effective.
They got me a VERY basic old school phone with no camera or internet option (very cheap at walmart by the way). They took away my iphone and put the sim card in the basic phone. It didn't even have a keyboard and I hated having to press the same button 3 times to get one letter and that really slowed down my texting.
I was still able to call and text but that was it. I have no resentment because I realize now that it was for my own safety and I actually thank them.

-8days