At the top of the chat windows in the games or in a private chat window, is a small enveloppe icon. When pressing that icon, the entire chat is send to the crew. Although it is unlikely that it will be read immediately, it will be handled at a later time.
If the situation is getting out of control and there is an operator online, the operator will help you control the situation. The operator may issue a warning to the person misbehaving or take any other actions necessary.
When no operator is online at the moment and the report chat option is not sufficient you can contact the Lobby Manager using the contact form.