I am asking this question on behalf of a friend. I don't own any Apple product. iPhone 6, iOS 8.1.1
My friend was so angry and he wanted to show me this picture. Two things made me laugh out loud, system services is consuming most of his mobile data, I asked about it previously.
What's funnier, is that the uninstalled apps are also using mobile data, everyday! He had to upgrade his mobile data plan because system services and uninstalled apps used half of his MB. He's paying way more!
In fact there's a joke in my country, that the carriers are offering iPhone 6 and 6 Plus users additional 300 MB for system services and uninstalled apps to use. I think something similar is on 9GAG too!
Now, I'm a programmer, I do apps all the time, and even I could not understand how an uninstalled app still use Internet! Those aren't apps who used to used Internet, no, those are uninstalled apps who are still today using Internet! …and everyday, the number of MB spent by uninstall apps increases!
Notice, my friend is a WhatsApp addict, uninstalled apps are using less than half of what WhatsApp is using—system services are using way more than WhatsApp.