Purchased 11 yr old a iphone 5 for Christmas. I set it up and all data is turned off. She can use it to chat with friends when home on wifi and she loves to facetime with them. Again, on wifi with data turned off. She used 5 GB last month, how??? I have gone through the entire phone and nothing is turned on for cellular, just using wifi at home. Outside of the home she just uses it to call or text me. help?