If you run into issues when you try to contact support through chat, try these troubleshooting steps.
Information on accessing Blizzard logs
How to report harassment taking place within Battle.net chat (mobile or desktop)
How to report a player who is threatening with harming another person or a place
Information on the Blizzard Voice Chat feature.
Troubleshooting issues using chat after your silence penalty has ended
How to manage your Battle.net profile visibility and chat settings
How to pop your chat windows out of the Social tab
Troubleshooting steps for Error BLZBNTBNA0000138F.