How to report harassment taking place within Battle.net chat.
How to report a player for cheating in Diablo III
Reporting your own behavior won't prevent action.
How to report players in Diablo III.
Information on how to report forum posts
Reporting an Exploit or Hack
Reporting another player that is using an offensive or inappropriate BattleTag
How to report harassment in Battle.net Groups
Information regarding harassment for streamers
Troubleshooting for error 315000