Here in the US we use permethrin based products or spinosad as they are readily available. I know that some have used Frontline (for dogs), or Adams flea and tick spray (applied with a q-tip to the areas where the fleas are) on the bird. I'm really ignorant of what is available to you in Australia, so don't know what to recommend specifically for products. If you have a local agriculture department there they may be able to advise you, or a vet that sees poultry.
The link I gave you before does mention one product available in Australia, maldison, I know nothing about it or it's use. You need to treat the bird, remove as many fleas as possible, I'd use tweezers for those that don't drop off. The skin under where they are attached will probably be inflamed, so you could use some plain antibiotic ointment there after they are off. You will also need to treat the coop and run where they live. The flea eggs and larvae incubate in the soil, so that needs to be treated at intervals to break the life cycle and get rid of them, or they will just keep coming back. Again, here I would use a permethrin or spinosad and spray it all. All bedding in the coop and nest boxes needs to be cleaned out, and replaced after treating the coop. Burning the removed bedding is a good way to ensure you don't just move the fleas to a new place. As with all infestations of lice or mites or in this case fleas, treating the host (bird) and the environment is necessary to get it under control. It will take some effort, I hope you can get them taken care of.
The link I gave you before does mention one product available in Australia, maldison, I know nothing about it or it's use. You need to treat the bird, remove as many fleas as possible, I'd use tweezers for those that don't drop off. The skin under where they are attached will probably be inflamed, so you could use some plain antibiotic ointment there after they are off. You will also need to treat the coop and run where they live. The flea eggs and larvae incubate in the soil, so that needs to be treated at intervals to break the life cycle and get rid of them, or they will just keep coming back. Again, here I would use a permethrin or spinosad and spray it all. All bedding in the coop and nest boxes needs to be cleaned out, and replaced after treating the coop. Burning the removed bedding is a good way to ensure you don't just move the fleas to a new place. As with all infestations of lice or mites or in this case fleas, treating the host (bird) and the environment is necessary to get it under control. It will take some effort, I hope you can get them taken care of.