Just got mine and my son's mobile bills and his is £30 over!
10 days at £3 a day of data usage
As lots of other threads have said, bill shows hourly data usage, ever hour all day even when phone is unused.
Charging at night in living room - data usage hourly
At school with phone asleep - data used hourly
Watching YouTube on WiFi - data used hourly
So pleased I saw all the threads before he came home was going to have words!
My bill is also showing this, but it's KB with mine and MB with his. No surprise it's eating very quickly into all of his 2GB.
A new SIM (with cap) is coming for him, which hopefully will bring it down to KB again. But how to I add my voice to all the others flagging this up.
Sounds like the phone is pulling data in the background, all smartphones do this in some way, there are some settings to set background data to only use WiFi.
Their billing system seems to aggregate usage hourly, so it shows up as hourly usages, even though the actual usage is spread throughout the hour.
You can also set up his phone to monitor each app's data usage, for example https://support.apple.com/en-gb/HT201299