Unfortunately for you, you will not be given answers on the forums. For starters, PC bans are handled by Steam, not ATVI. Second, even if they were handled by ATVI, bans are the result of a thorough investigation and are not subject to review or appeal. Furthermore, it is a violation of forum rules to discuss bans within the forums. There will be a forum CS tech or moderator that finds this thread shortly and they will reconfirm everything I've mentioned here.
That said, from what I have seen in other VAC bans is that the software detects cheat software throughout your PC. So even if you've never used the software, merely having it installed on your PC will trigger a ban.