Top agencies for TVC's??

Hi all. Just wondered if there was an agency in Sydney whose speciality is TV commercials? Many seem to be mainly for extras. I want to know who is the 'creme de la creme' of agencies for ads. The agencies that don't advertise for talent, and who pick and choose who they put on their books, know what I mean? I need to test whether I'm trully in the right industry. Can anyone help?? Cheers, Linda