Inappropriate ticket sales leaving people stranded during COVID at Melbourne airport

I was left stranded and depressed after being denied boarding for ticket which should not have been sold to me or cancelled before hand with explanation that only SA passport holders and not permanent residents would be allowed to board the 4th of May 2020, 22H30 from Melbourne Australia to Johannesburg South Africa. I rebooked the ticket several times after cancellations and surely someone should have informed me that the flight was only for citizens when they confirmed my passport details. I even left a flight that could have taken me home with another service provider. I am stranded and destitute and hope to get either money back urgently or be taken home. My details can be confirmed with South African institutions such as the commission.