works out £2000 when I added stopovers in sin + bkk on aa.com...

when i searched tip-syd direct in F and selected fully flexible ticket, it came to £1698 though. See fare rules below:

Detailed Fare Rules
Click on the fare basis code for each city pair to view its particular fare rules.
NOTE: The most restrictive set of fare rules applies to the entire itinerary. In addition other fare rules may apply


City Pair Fare Basis Display Below
TIP to LHR F
LHR to SIN F
SIN to SYD F
SYD to SIN F
SIN to LHR F
LHR to TIP F



Minimum Stay Not Applicable
Flight Applications Not Applicable
Day Time Application Not Applicable
Penalties Not Applicable
Refunds Reissues Not Applicable
Maximum Stay TRAVEL FROM LAST STOPOVER MUST COMMENCE NO LATER THAN 12 MONTHS AFTER DEPARTURE FROM FARE ORIGIN.
Embargo Dates Not Applicable
Surcharges Not Applicable
Advance Reservation Ticketing Restrictions Not Applicable
Sales Restrictions TICKETS MUST BE ISSUED ON/BEFORE 31MAR 05.
Eligibility NOTE - EXCEPTION - UNACCOMPANIED INFANT NOT ELIGIBLE.