I have to say that they are treating those on the hold pretty poorly. No updates, don't respond to calls or emails. No other industry would string their applicants along like this.....
Do you want to work for them or not? Its their play pen and they can pretty much do as they want in it. If you want to work for them then accept that. If not, then make tracks elsewhere.
At present it is an employers market with plenty of qualified applicants with the likelihood of plenty more joining the ranks of the experienced and willing before there will be any substantive changes in this particular job market. With QANTAS calling a truce in the capacity war it has been waging with Virgin I expect the need for more fresh crew will be even further reduced. Get used to waiting.