Dave, you could purchase a QF fully refundable fare for the same day - say SYD-NCL. This would get you lounge access in T2, then once in, use the couresy phone to cancel the flight for a full refund.
This might not be ethical, but would work. Also note that soon you might lose the 1% service fee for billing it to your credit card, as well as costing you the government charges for credit transactions, so it is not a no-cost option, but is a very low cost option, unless the refund takes as long as that for IainF.