MBA Automatic Updates

Guys,
I am having an issue that I can't seem to put my finger on.

I work in an area that requires me to stay on site for 2 weeks at a time.
We only have HughesNet internet with 450 Mbytes a day download allowance.
Everything has been fine for several years until I purchased my MBA last month. It seems that we exceed the allowance every night. The only thing that has changed in the past year is the MBA. I have turned off all automatic updates, ( I Think) however I am new to Mac & OSX. This only happens at night, and like I said. The only new item is the MBA so I'm wondering if I have maybe looked over something that I should turn off, could it be something updating that I don't know about. iCloud is off and I'm signed out, automatic updates are turned off. It's now someone getting into our wifi as the closest neighbor is approx 3 miles away. No one can even get close to my location unless it's by helicopter.....

Could it be that I looked over something on the MBA? Is there anything else I need to turn off?

Thanks guys,
Kyp

I do agree, however I shouldn't have to.....
Thanks,
Kyp