Do you have a router? Is it secure? Could someone have gotten the password? Do you use other devices like cell phones and tablets on a home wifi router? Do you have Dish or DTV receivers connected, Roku, NetFlix, etc? Gaming consoles, smart TVs?
If so and you still don't understand email firstname.lastname@example.org with you questions and account information and, somone there will be happy to expalin what each type of usage is and, what sort of devices used your connection or, at least what applications those devices used on your connection.
Hi Betsy, We would love to look into your issue. When you return home, please send us an email to email@example.com with your account and contact information. We'll take a look at your account and data usage.