NOTE:
I cannot do anything about mobile / CGNAT IPs which constantly change sorry ! You need to use a fixed IP which hasn't been used for attacks before.
If your still banned after 3 days,likely your request to unban was not successful.
I suggest you use a VPN to access and register on the forum for a account as unban reqests are more likely to be taken seriously.
If your a banned member, shout out on any other popular Atari groups and likely someone will respond whos a forum moderator or member.