I was banned for cheating in the coliseum and it was not my fault!

Nah, the accounts done, mate.  There's no going back from that.

The issue is you cannot rewind what the cheat has done.  As the account interacts with other players' there's no way they can allow a hacked account to re-enter the game.  Sorry, but you have to let it go.

it was not my fault................he admittedly told me he downloaded cheat software on my game.

Well....other than this legitimately being a very large percentage excuse (my little brother did it); it is your fault.  If you've allowed him to have access to your account (also against the rules) and he (for whatever reason) has decided to and knew to cheat on your game account, then that is your fault.

What done is done.  I'm very much afraid you'll have to move on.  From all I have seen in the past with cheating, having access to that account again is impossible.