I have yet to get a response from Verizon on why my droid turbo is using so much data. It is apparent their is some flaw when my phone shows I have used 100 mb so far this billing period and Verizon wireless shows I have use 1.17 gb of data. I have checked all of my apps to restrict background data and yet it is using data like it is going out of style. If somebody has a solution please let me know.
Have you Checked to make sure your apps are not running all the time.! check that and if not using the phone at night you might engage the Battery Saver & Give this App a Look: System Panel it comes in a Free or Paid Version minus the Ads..
Install it and see what your phone is doing it's a Good App and can tell you quite a bit about what's going on, I've used this App 4 years now installed it on my first Android phone a Droid X.. To add: it can also tell you the temperature of the phone's CPU and it's battery and how much internal & external Data that has been used..
I had the same problem. After checking with other Turbo users on another board it turns out that even when you sign into wifi Turbo was using data. I believe this issue was supposed to be fixed in the last update, but I'm not sure it has been. I called Verizon today to get a refund for the $55 in overage fees I got in my first month with the Turbo. Verizon gave it to me, but in the course of the conversation the tech support guy asked me to turn on airplane mode and he sent me a text, which came through fine. He seemed fairly shocked about that, but still said that "we can't be sure what the source of the problem is, it could be your router." My router works fine and we have no connectivity issues with all the other devices in the house including the other cellphone, and it would have nothing to do with texts coming through. So, that's my experience with this issue, but at least I got a refund for last month's overages.