"Incorrectly billed for a bulk-billed test"

I received a blood test at Western Diagnostic East Victoria Park. I had no complaints about the procedure, but was incorrectly billed at the time. My procedure should have been bulk billed with no out-of-pocket expense. My GP confirmed this and advocated for me to follow up. I have now called three times in the past month and still have not received a resolution. Each time I have called, I have been promised a follow up call, given my email and phone number and had no further action. I have now spent almost three hours on the phone. Based on my experience, I would use extreme caution when paying out-of-pocket for this provider.