I phoned & asked my bank (WBC) 4 years ago the same thing....To my astonishment they said yes.
Try the same! If you dont ask you dont get.
CBA have phoned me and advised that if I complete the forms now to refix for 3 years they will honour the current 3 year fixed rate. Evidently anyone can do this within to 42 days of there fixed rate finishing. And there is no fee involved.