I totally understand your frustration!! I've had the same issues. Sometimes they get through and sometimes not. Humaworm seems to get through most of the time for me. You could apply for an import permit. Do a search on this forum as the issue has come up before. I've forgotten why I did not go down that route at the time (about 2 years ago) but another Aussie did. I may look into it again.
Another option is to see a naturopath locally. I have been given a herbal parasite cleanse called 'parex'. it is practioner only so you would need to see a naturopath. It is very similar to humaworm but does not have psyllium. You could alawys buy psyllium husks they are very cheap.
I would prefer humaworm as I"ve gotten great results from thier product before and why try something else I also like all their other products, but if there is no other option this might be a good alternative at least for the parasite herbs.
Let us know how you go!