Since we got a new Xs for my son and a new Xr for my daughter, the data usage has skyrocketed and they aren't using it for anything more than what they did before. over the last 2 months we have started going over our data AFTER we purchased these 2 new phones. This month both phones have used 7gb each with 12 days left in our month.
Sounds like you have WiFi assist turned on. The first thing any iPhone user should do is go and turn this off.
settings > cellular > WiFi Assist
It's so important to know about the usage on your account. I regret to learn of any confusion, and I'm eager to assist. Please allow me to explain that we have a Data Utilization Tool for our customers. The Data Utilization tool uses 12 categories to show a visual estimation of how your devices use data on the Verizon network. In addition, the categories are intended to provide a general understanding of how your devices are using data. Check out the details in the following link. Just click the link, then scroll to number 1 under the section marked "Troubleshooting and Data Management:" http://spr.ly/6603Egzhl
Additionally, I want to let you know about Smart Family,which is a service that gives you parental controls to help manage your kids' smartphone use. It's a great feature and it allows you to:
Just click this link to see the information about Smart Family: http://spr.ly/6604Egzhm