If you're banned on alteriwnet, oh my oh my. You're banned.
There are many methods of unbanning yourself, posted here. If one of these does not work, try the next one.This is to minimize all threads in the forum begging for unbans. Be aware, these unban methods are for dynamic ip only.
[WORKING] Method by Markus - Spoofs your MAC address, which generates a new XUID.
This will be updated when new methods are presented. Remember, if you have static IP, you must contact your ISP for a new IP (or use some other method) that's all I know of. Dynamic IP, well you're lucky.