From
http://www.qantas.com.au/info/flying/A380/schedule
Sydney - Los Angeles QF11/12- On selected flights - Service departs Fridays, Wednesdays and Sundays
This is NOT a last minute change which their disclaimer tries to cover, I would be ringing QF and advising them that you booked the A380 based on this and would like to be moved at no cost to the A380 flight.
The 744/A380 experience is NOT the same and you are not getting what was advertised