When I made my reservations before travelling to Australia I found that most places were willing to accept my credit card number to hold my reservation.

At my explicit request they did not use the number to withdraw any money, but it used as a gurarantee. I then paid in cash (Au$) at the time I stayed in each place.

You might inquire if these two Australian firms are willing to do the same.

Good luck.

Have fun! Debby - Israel