Why Is My Phone Using Data When I'm Not on It?

If the phone is in standby and not connected to power, it will switch to cellular data. Even so, that seems excessive. WiFi assist will use cellular data if the WiFi connection is exceptionally poor or not working for some reason. If you go to Settings>Cellular, you can see what's using your cellular data.

Why is my phone using data when not in use?

If your data is turned on, then you may be charged for background data. Background data is data that your apps are constantly using, it could be when your phone is in your pocket or even when you are asleep! Some apps - such as MyDigicel - do not incur a charge for this background data.

Why is my data draining without use?

Check Data Syncing Intervals

If your calendar, contacts, and email sync every 15 minutes, it can really drain your data. Have a look under “Settings” > “Accounts” and set your email, calendar, and contact apps to sync data every few hours or set them to only sync when connected to Wi-Fi.