Have you hung up and called again and gotten the same answer?

Have you asked for the international rate desk as was mentioned earlier?

I hope it works out but normally trying to piece different tickets together like this isn't a great bargain -often the cost of XXX in Asia to Australia round trip costs almost as much as a cheap LAX or SFP to Australia round trip, you don't burn as many miles and you earn miles on the paid ticket. But keep checking.