Just a few links that could be usefull.

ARA Car Rental 
22 Hanbury St, Mayfield  NSW  2304
Tel:     +612 49 677079    or     1800 243 122 (within Australia)
Fax:    +612 49 676424

129 Melbourne St, East Maitland NSW 2323.
Tel: +612 49 345033
bookings@ararental.com.au