Despite the fact I employed no nonsense Tinywall, Windows 10 still proved that it's still the host OS. Tinywall worked against all Windows and third parties apps except Windows Update. Even if you untick Windows Update and Windows Store Update in the "Special Exceptions" of "Tiny Firewall Settings" section, Windows will still update.
Sweating!

The solution - Edit the Group Policy
To finally stop Windows from updating and licking your data, you will have to edit the Group Policy. To do that follow the instructions below:

From Windows start menu find and run Command Prompt with administrator privilege

Type gpedit in the command prompt and press enter
(Local Group Policy Editor Will Appear)

Goto:
Computer Configuration -> Administrative Template -> Windows Components -> Windows Update

From the list on the right find, open, edit and save each of the followings:

* Allow updates to be downloaded automatically over metered connections **set to Disabled
* Configure Automatic Updates **set to Disabled
* Specify intranet Microsoft update service location **set to Enabled
(Then type localhost inside all the 3 boxes)
* Remove access to use all Windows Update features **set to Enabled
* Do not connect to any Windows Update Internet locations **set to Enabled
* Turn on recommended updates via Automatic Updates **set to Enabled


Beware there is danger of not allowing your system to update with latest security fixes. Do the above if you know what you are doing.

Set your connection to "metered connection"

What i notice on my window 10 is that there are times it will take less data, and other time it will drain all my available data...if I mistakenly use it with my night plan, once I on the hotspot, it will drain everything in less than 5min.

tempest01:
Set your connection to "metered connection"

It failed sometimes and Windows 10 will surprisingly drain your data.

Windows 10 gave me so much trouble draining my data. I switched to Kali Linux.