To change the legal owner of an .au domain name please visit:
https://www.enetica.com.au/register.cgi?action=reg_transfer
A transfer fee of A$89 is applicable but covers the new license in the new owners details (a new 2yr license).
Please call Enetica on 1300 720 043 or +61 2 9779 1166 once you have sent the fax as advised on the form at the above link.