This is exactly why my middle difficult child (15) can not have access to ANY (she is banned at school and I have to sign off on it every year) computers and why I rethought her birthday gift of a cell phone, which we had put off too and ultimately decided no way she would be getting one still.
On the computer issue, she had in the past accessed all kinds of sites, gone into chats, twitter, etc. and created email accounts and gained access for things she shouldn't without permission and used MY email or my SO email address for verification (this is how she got caught time and time again!). While we didn't allow her to use the computers at home because we saw what she was doing and where she was going, she would use them at school and her grandmother's house (even when she was supposedly being supervised but apparently not close enough!). At one point she was involved with emailing a perfect stranger (adult) from Australia and if I had not intercepted the email she would have been CALLING him as he gave her his phone number and she would have called since she has no awareness of stranger danger even still (cognitive issues). I can't stop her at friends' houses, though I try as much as possible but now it's come that she doesn't go to anyone's house mostly because peers don't get along with her whether it's her controlling issues, immaturity or a host of other reasons. She just doesn't keep friends long. The other reason of not going places is her ability of lying, manipulating, and triangulating adults and others so well. We been placed in a good many awkward/bad situations and I won't go through that anymore.
As for cell phones, I learned that while I could put parental controls on it through ATT (would restrict usage-time, minutes, numbers, etc) it wouldn't restrict data or pictures and in order to track any of that I HAD to get a smart phone to use that app mentioned. Then I'd have to pay for a data plan to basically NOT use as we'd be blocking ALL internet usage (which WOULD restrict picture messaging completely- ie, I could pay for plan but then block it but HAD to pay for it to begin with-dumb!). I could buy her a simple basic phone but again, she would and could still text and take pictures and I'd have no way of blocking or tracking that without that app and you can not do that without having a smartphone as basic phones don't accept apps!
Call it socially crippling her at 15 but that is basically what we have done and have to do sadly for her own good but she has done this to herself. My oldest difficult child got a basic cell phone at 13 due to her extreme anxieties when she left us (like school dances or activites, needed to have contact) but she was much more mature and responsible and I NEVER had to think about trust issue, even to this day. Oldest difficult child didn't use any technology either, by choice, until she started college either. We had to convince her by then and she realized she HAD to have a computer and accepted it by then. She says she was "living under a rock" her teenage years because she was always just interested in reading books and nothing more. No boys no nothing. She's sort of making up for that now though at 20! LOL Youngest difficult child is middle of the road at current. He can have a "little" trust but must be watched carefully. Darn kid knows how to get into things so I see potential brewing for sure!
Sorry to have digressed a little but just wanted you to know that there are other difficult child's out there that have to be on "lock down" too so you don't feel like your's is the only one.
