Data usage insane

iPhone cellular data options

To turn Cellular Data on or off, go to Settings > Cellular. To set options when Cellular Data is on, go to Settings > Cellular > Cellular Data Options, then do any of the following: Reduce cellular usage: Turn on Low Data Mode, or tap Data Mode, then choose Low Data Mode.

View or change cellular data settings on iPhone - Apple Support

To see how much cellular data you've used, go to Settings > Cellular or Settings > Mobile Data. If you're using an iPad, you might see Settings > Cellular Data instead. Scroll down to find which apps are using cellular data. If you don't want an app to use cellular data, you can turn it off for that app.

Use cellular data on your iPhone or iPad - Apple Support (IN)

If you use an Exchange ActiveSync account, it might continue to use cellular data even if you turn it off for Mail and Calendar. To see the cellular data usage of your Exchange ActiveSync account, go to Settings > Cellular > System Services.