My SA has communicated with me through E-mail and calls.
She has alternatively been slow to respond and very proactive.
After being through the order process once before, I now know what to do and how to do it. So I try to be a little bit ahead and when I complete the next thing in sequence, I send a message to her about what I've done is case there is something she needs to do on her end.
While not perfect, it seems to have worked out reasonably well so far.
Waiting on a VIN and Delivery date from Tesla but more importantly now, the Title from American Honda for my current car so I can fund my down payment.
Anyhow, phone and E-mail is the answer to your question.