What console do you game on? Using "Gamertag" makes me think XBox, making this the wrong section, but no worries. I'll assume that this is for Black Ops 2, too? Just asking to check, that is all
It's highly unlikely that they would have done anything to affect your console. If they had the ability to cheat then they wouldn't need to boost, so I think that can be ruled out unless there is any other evidence to indicate otherwise.
First thing you should do is check to see if you are able to connect to the internet with any other game or application on your console. Use the internet browser, youtube app, etc.
From the time of this reply the status of the online for BO2 is perfectly fine. So, if you are still having problems, then there is something else causing a problem. I have no doubts that ATVIAssist will spot this and take over, though.