Where? Where? What's the number!?
Unfortunately, I suspect you're referring to the old North Sydney AA office which, as far as I know, was closed a year or so ago ....
AA SYD still exists; they've moved to Mascot. And they don't deal directly with pax these days. You get routed to IndiAA to book flights, and your records get sent to the AA office at Mascot for ticketing.
Number is 1 800 673 486.
IME IndiAA is quite ok at straightforward round trips. I've done a couple of ex-MEL itineraries with them thus far, and some domestic USA flights since AA.com doesn't accept Aussie credit cards. I've yet to try redeeming an AAward through them. But don't even think about setting up an ATW with them unless you've got LOTS of time and patience.