My iPhone 7+ is using a lot of data (WiFi and mobile) but I don't know why. I first noticed the issue when my phone seemed particularly hot one morning, and later discovered I had used 15GB of mobile data in one day. I contacted Apple who unhelpfully suggested that I switched everything off (background refresh, email, etc) to fix the problem. I switched mobile data off completely to prevent overage charges. I then ended up buying extra data as having a mobile with no data is pretty crap. When using mobile data, I can see which apps and services are using data. I switched data off for most apps but I noticed that system services/media services was using most of the data (and I can't switch that off separately). The music app had mobile data switched off so I'm not sure what the media services is? I downloaded a data usage app which shows how much mobile and WiFi data I am using. It says I use 1-2GB of WiFi data around the time I wake up each day. Apart from switching my alarm off, occasionally checking a few emails or the weather before I get out of bed, I hardly use the phone when I wake up. As it's WiFi, I can't see what activity is using the data. Of note: I have iCloud Photo and Apple Music (inc Match). I use Google/OneDrive apps but background refresh is off and neither can use mobile data. I've had some issues with downloading updates for apps. I click update all, the circles appear and then update appears again. Updates eventually happen. Seems better with 10.1. App store has mobile data switched off but it could be using WiFi. I updated all apps last night so it is not the reason for the 2GB used this morning. I have a problem with iCloud backup (in that it hasn't backed up for months) but I think backups are attempted when the phone is plugged in and on standby (which wouldn't explain why the data starts the moment I wake the device up). I restored this device rather than a clean install. I should probably do a clean install of iOS but I hate having to reinstall all the apps individually (and losing some of the data). Plus downloading all music again is a pain when you have Apple Music/Match (it's not the same as transferring your own music over from iTunes). Anyone else experiencing data issues or have any ideas what could be causing my high data usage?