Focus

Their web page is here and the phone number is (02) 4702 9400

But it's probably easier to make a booking online from a link in their web page.

There is a note there too saying:

We're currently open by appointment only, and are unable to welcome walk-in customers at this time. Shop one-on-one with a Specialist by reserving a shopping session, make an appointment to connect on a carrier plan, pick-up online ordersand get support at the Genius Bar by making a reservation.

It's the same at Castle Hill and Hornsby, if they are near you. I don't know that part of Sydney very well (been to Penrith though) but in any case it seems to be universal at the moment that walk in consultations are not happening. It's the same down here in Melbourne.