Well, if you are banned I guess you'll have to wait that out. Don't hack, don't flame, don't teamkill, and don't do anything against the rules of play. You'll learn your lesson. The mods are good at making sure they only ban the right people. I deffo say you should think hard on why you got it and don't do it next time.
Alternatively, you can always get a new steam account, buy the game anew, and be a better person. There is no way to change your ban respectively.
How do you know it's a 7 month ban? you said it was 2-3 months in the shoutbox. Enlighten us.
Edit: In your post history, you say that you have been banned before. I guess you didn't learn your lesson.
who the hell are you ? you cant judge me . i got ban but i dont know why i got and how long it takes . mayt.