I need help, please. My first online live class it today in several hours. I launched a quick test session and to my despair, hear a terrible echo of myself speaking, even before starting the broadcast when audio and video settings are displayed. What should I do?

I emailed the support a little while ago, and  right now on the Zoho general phone support waiting for almost half an hour for someone to pick up... 

I don't want to show up like this to my first students who paid for this class...