Who can unban my account "captchacoins"
First , If you got banned then you already got the some mail for "ban appeal" so you should appeal on it.
Second, If you got banned, then you can only made a post of it in "Meta" section. Posting in any other forum is considered is as ban evasion.
Third, Ban are not limited to account but they are user specific. If one of your account is banned it mean you should not access forum with any new account also.