The iPhone 5 on our plan data usage has always been high but since its been upgraded to iOS7 its out of control. When home ~14 hours a day its connected to wifi, applications configured to use wifi when avail, no stuck e-mail. After reviewing data usage log high usage times are random and often when the phone is not is use.
Data usage this month
Droid Maxx Android 1.11GB Heaviest data user - monitor business IP cameras remotely, multiple e-mail accounts, web application, etc