Cheers, I just wanted to check protocol for getting a passport - apparently the rules have changed and proving citizenship is a historical journey up the family tree rather than just the provision of your own birth certificate.
But you do only need the birth certificate of one parent. What's mum's citizenship status? Can you use hers or is she a foreign national?
If mum isn't an option, then I suggest contacting the Office of Births, Deaths and Marriages to discuss what pathway needs to be taken to access dad's birth certificate. If they can't help, contact the Department of Home Affairs about applying for evidence of citizenship. There is usually an avenue for exemption where consent of multiple parties is ordinarily required.