I know how you feel. I have private health cover and I find the cost of scans and X-rays is particularly high. It's always worth asking. I was only charged $650 for radiotherapy for 6 weeks as a private patient, after asking if it could be cheaper. Chemo was fully covered.
My doctors have never charged me an excess, even for ongoing reconstruction. I just pay $500 excess hospital cover. I think it's the scans that cost me a lot. I like being able to choose my doctor, hospital and have more control over my treatment. For me, health insurance is essential. I have had all of my treatment in the same hospital for over 2 1/2 years with the same team. That's why I have private cover, but I always ask about the cost and the options. You are the client, stand up for your rights. All the best. x