An update for anyone that is interested in my trials and tribulations in trying to book through AA. I have almost given up of trying to get this itinerary ticketed. I don't know what to do other than to call the UK and try to get them to ticket but I think this booking now has too many negative remarms on it.
Just before I was due to depart for BNE domestic earlier this afternoon I got a rather disturbing call from a rude, arrogant, disgusting person, I use this term very loosely because he is a lowlife and behaved more like an animal, who said there is no way this itinerary is going to get ticketed. When questinoned on a number of issues the excuses he gave kept changing from the booking is not valid for AA to issue, only BA and QF, I used UK as the country of residence even though I live in Australia etc. When I questioned him on why the airfare was available on the AA website but not for sale his stupid remark was they had to list all available airfares but do not necessarily have to sell them. What a load of hogwash.
Just a word of warning of anyone trying to book via the AA website with an Australian address and credit card but specifying the country code as the UK that the checking process has become more detailed. You may get away with it but you may also be left high and dry. Not really all the hassle. I could actually try to stuff them by using a valid UK address but right now I want nothing to do with AA or their poor excuse for an airline.
I have managed to find a similar itinerary on Expedia for only ~A$210 more than AA website but the routing is BKK-SIN-SYD-BKK. I can leave BKK the day after with the exact same itinerary as mentioned on this thread, BKK-HKG-SYD-BKK, for only ~$220 more than the airfare on the AA website. This looks to be the best option.
And in order to calm me down when I got to the airport I was given a boarding pass of 1J for my flight to SYD. It is almost as if QF knew I was in a state of distress. To serfty thanks for the phone call and the advice.