Ana, you may want to send out a tweet on your account, I have links to a few virtual assistants in Melb who follow me, so happy to RT for you.
You may find $20/hr a little light on though for a professional service. I have a uni student who helps us all out in the office 1 day a week, but he at 18 yrs old just scans and shreds, lifts heavy things, changes light globes ( funny that I do all that myself for the renos but not in the office) no phones or thinking required.
All the best with the search.
Jane