::::Sorry, but that's not true. The Statue of Westminster changed constitutional law without changing the wording of the Constitution Act. The Australia Act did so again. There was no requirement for the Imperial Parliament to change the wording because no Westminster Parliament can bind a future one. The Commonwealth of Australia Constitution Act created one constitutional settlement. The Westminster Parliament then created a new settlement via the Statute of Westminster with the proviso that the Commonwealth had to opt in. It did so. 

 ::::The other point you make is that the Royal Style and Titles Act 1973 only applies to the current Queen. That is false for two reasons. First, statutes that discuss the sovereign routinely refer to "the King" or "the Queen", as the case may be, and it is understood that the provision also applies to future holders. Second, you seem not to have read the act. It authorises the Queen to issue a proclamation changing the Royal Style and Titles; it does not actually set the words in stone, it just says what form is acceptable for the proclamation the Queen was to issue. Thus, even if the lack of "heirs and successors" meant anything normally, it wouldn't here because the act was authorizing a one time event that happened in October of 1973. 

 ::::Frankly, the assertion that the GG is the representative of the UK crown, rather than the Australian one, is the one that needs support, and from more than just looking at one line in the Constitution Act and ignoring every law of constitutional significance issued thereafter. That is especially true since you acknowledge that there are separate Australian and UK crowns, but still assert that the Governor-General is appointed by the latter. Do you have any support from constitutional law experts or scholars of any kind? Because there is a logical inconsistency. Who advises Elizabeth II on whom to appoint as Governor-General: David Cameron or Julia Gillard? Julia Gillard has no power or authority to advise the Queen in right of the United Kingdom on anything whatever. If it is truly the case that the GG represents the Queen of the UK, then David Cameron would advise her on the appointment. I think we all know that is not the case. Also, as mentioned below, the commission for a new GG is issued by the Queen with her Australian title, meaning she makes the appointment as Queen of Australia. Otherwise, her title on the commission would read "Elizabeth the Second, by the Grace of God, of the United Kingdom of Great Britain and Northern Ireland and Her other Realms and Territories Queen, Head of the Commonwealth, Defender of the Faith." -