Aight, so I tried joining the Vanilla server (I had a client and have replaced the realmlist.wtf with "set realmlist logon.elysium-project.org" and checked for any mistakes, none.) and I still got the same problem. "This World of Warcraft account is no longer available for use..."
Update #3: I have made a new account, and tried logging in. It worked, but now the problem is: Why is this account banned if I just made it 1 day ago?