My wife's iPhone 5s running iOS 12.1.4 is using up our internet daily allowance with no apps running. Double clicking on the Home button shows no apps listed. I turned off the wifi from all other devices except her 5s and watched our data slowly diminishing. Turning off the wifi on her iPhone, the data stops. Our daily limit is only 475 MB. Is there any way to find out what exactly is using up our data on her iPhone?