NetworkManager keeps enabling wlan0

[TheChosenOne]

I've set a start up script to disable the wlan0 interface. This works, shortly after startup this interface is disabled.
But when I check a while later (~15 min), this interface is enabled again.

I've added next line to NetworkManager.conf:
$this->bbcode_second_pass_code('', 'unmanaged-devices:mac:[mac address]')
but that doesn't fix the problem.

I have no idea what keeps enabling it.