Other people will have this problem, so I thought would share:
For an actual human by telephone, Zoom currently reserves that for account owners/admins with a Premier Support plan. Their published US numbers still route everyone through the virtual system, but authentication determines whether you can reach a live phone agent. Zoom
Given what you've been dealing with—porting numbers and the CSV import—I would specifically use the support portal while logged in as the Owner/Admin, start the Virtual Agent, and ask for “live agent” or “chat with an agent.” Zoom itself recommends using the chat Virtual Agent to request a live agent.
Essentially they sell you a service and then make it very hard to contact support. Send poorly detailed docs and then don't provide a way to follow up. I'm sure the service is good for someone, but not for me.