My wife and I recently updated our iphones to ios 11 last week. I have a 6s and she has a 6. She averages only 1.24 gb a month. I got a message saying we were close to our limit and I took a screen shot of the data usage in the AT&T app. She was at .9 GB used 24+ days into our billing cycle. As of Sunday night she's up to 5.58 GB. She hasn't used the phone much at all outside of the house since Thursday. We have wifi assist off and auto updating apps off as well. I called AT&T today and they said they are seeing data requests every 3 hours from 400 mb up to 1 GB each time. I locked down the data usage via the app now. They advised to go to the AT&T store and have one of their people look at it. She just came home and said they had no clue on how to fix it or why it was happening. They did say the OS seems to be incorrectly tracking the data usage incorrectly. I just backed up the phone and will be doing a "Reset all Setting". Any other ideas?