So, if any customer of any ISP that has data caps ... needs to understand how to manage the operating system and the software installed on that operating system.
Many Microsoft Windows users are unaware of the changes brought about by Win10 and to some degree the changes in update format to Win7 and 8.1
An ISP is contracted to deliver (and support) Internet services to the Modems LAN port.
An ISP is not obligated to provide "IT services" in respect of educating users on how to operate their computer.
IF you have Win10 updates can not be disabled unless .........
#1: you are running the Enterprise version of Win10
#2: You have performed a registry hack on the OS
#3: You ONLY connect wirelessly AND have set your Windows WiFi connection to "Metered"
#3.5: You recheck the "metered" setting after every Win Update as many of them re-set settings to the default values.
"I even had data used while my devices were off and NOBODY was in my house! Amazing!!!"
Again, run a modem isolation test:
Take a screenshot of the status meter and note the time, then disconnect the LAN cable
Leave cable disconnected for a period of time (over night?)
Reconnect the cable, note the time and immediately take a screenshot of the status meter.
Post the "shutdown" screenshot and time
Post the "startup" screenshot and time
The Modes will then validate the usage and shutdown from the modems log indicating the 13.1.1 error the modem will generate from the LAN disconnection.
Here is the graphic showing the steps required:
Are you sure you have the option to share updates turned off? That can be a huge data drain.