GPA hasn't really been an issue in Australia for jobs. Most places just want your qualification once the job has been offered, particularly governmental jobs. Most universities here don't even include it on your academic transcript.

Edit: I failed a subject in my undergrad and it's never been raised as an issue. 21 and partying was the reason. I've worked on government agencies for well over a decadf. Failed subjects wouldn't be on your certificate either. Workplaces consider your university as the gate keeper of capacity. If they admitted you to the degree, you're qualified enough.

Can you sit the exam again? Doctors here, for example, fail exams all the time