That said, if playing the latest version of Warcraft III, map based "banning" is a lot more powerful than in legacy versions. Players cannot change their name in under 30 seconds like they could in the past. Further more to create an alternative account they would need purchase either a copy of Warcraft III Reign of Chaos or Warcraft III Reforged to be able to play Warcraft III so the process is not free. Even name changes are not free, if at all possible.
As such updating the map every few weeks and adding the people to a hard coded ban list might be sufficient to keep them out of playing the latest version of the map. If you do use this approach consider removing bans after 2 years or so as chances are the player will not be a problem then and if they do play again hopefully they grew up a bit.
If using a legacy version of Warcraft III then name changes are probably quite easy to do, with lobby spoofing even being possible. Nothing much you can really do about this...