First, find out the nameservers for com.au:
$ dig com.au ns
[snip]
com.au. 86400 IN NS audns.optus.net.
com.au. 86400 IN NS udns3.ausregistry.net.au.
com.au. 86400 IN NS dns1.telstra.net.
com.au. 86400 IN NS udns2.ausregistry.net.au.
com.au. 86400 IN NS udns4.ausregistry.net.au.
com.au. 86400 IN NS ns1.audns.net.au.
com.au. 86400 IN NS udns1.ausregistry.net.au.
com.au. 86400 IN NS ns3.ausregistry.net.au.
com.au. 86400 IN NS ns3.melbourneit.com.
com.au. 86400 IN NS au2ld.csiro.au.
com.au. 86400 IN NS ns1.ausregistry.net.au.
com.au. 86400 IN NS ns4.ausregistry.net.au.
com.au. 86400 IN NS ns2.ausregistry.net.au.
[snip]
Then check a sample of those nameservers to see if they have the new delegation for your domain. E.g., for theage.com.au:
$ dig @ns1.audns.net.au. theage.com.au ns
[snip]
theage.com.au. 14400 IN NS ns1.fairfax.com.au.
theage.com.au. 14400 IN NS ns2.fairfax.com.au.
[snip]
and
$ dig @ns3.melbourneit.com. theage.com.au
[snip]
theage.com.au. 14400 IN NS ns1.fairfax.com.au.
theage.com.au. 14400 IN NS ns2.fairfax.com.au.
[snip]
If any of the nameservers show the old delegation, then the update is still propagating.
"dig" is your friend when it comes to DNS; spend some time learning how it works, and how the DNS system works. (I should take a bit more of that advice myself -- I still don't think I've got a complete understanding of DNS.)