Look like the methods need revisiting since a new booking engine was released in the last couple of months.
A manual comparison with ExpertFlyer shows the an inclusive $426 Flex fare on Feb 16 books into M class (MQFLEX).
I did this by comparing the fare breakdown as shown in the recently introduced "Basket" with results from ExpertFlyer. ($362.82base fare)
Results from ExpertFlyer.com
Code:
Fare Information Search:
Departing MEL on 16/02/17 for CNS, Flying QF, Purchasing at MEL, Viewing in currency AUD, Validated Results
Fare Basis Airline Booking Trip Type Fare Cabin Effective Expiration Min/Max Advanced
Class Date Date Stay Purchase Req
...
MQFLEX QF M One-Way 362.82 (AUD) E 03
MPXI QF M One-Way 363.09 (AUD) E
MQFLEX QF M One-Way 363.09 (AUD) E 03
MPXI QF M One-Way 372.74 (AUD) E
MQFLEX QF M One-Way 372.74 (AUD) E 03
KIX QF K One-Way 422.17 (AUD) E
KQFLEX QF K One-Way 422.17 (AUD) E 03
KIX QF K One-Way 424.64 (AUD) E
KQFLEX QF K One-Way 424.64 (AUD) E 03
KIX QF K One-Way 431.83 (AUD) E
KQFLEX QF K One-Way 431.83 (AUD) E 03
HQFLEX QF H One-Way 485.82 (AUD) E 03
HQFLEX QF H One-Way 493.73 (AUD) E 03
HQFLEX QF H One-Way 495.47 (AUD) E 03
BQFLEX QF B One-Way 663.09 (AUD) E 03
BQFLEX QF B One-Way 670.09 (AUD) E 03
BQFLEX QF B One-Way 672.74 (AUD) E 03
YQFLEX QF Y One-Way 826.73 (AUD) E 03
YQFLEX QF Y One-Way 836.38 (AUD) E 03
YQFLEX QF Y One-Way 844.64 (AUD) E 03