What you have reported the Qantas person as telling you is wrong in every significant aspect (except perhaps the price). Unfortunately there are a lot of people in the airlines who have very poor knowledge of these tickets. Because of the complexity of these tickets AA runs a dedicated Round The World desk with people who do know what they are talking about. If you could route you transatlantic flight on AA and have a means of calling the US at reasonable rates then you could deal directly with them on this: +1 800 247 3247.
Personally I have also had good experience dealing with the Cathay Pacific phone ticketing office in London but since you appear to have no longhaul flights on CX they may be reluctant to handle it.