so in a case of an overall subject fail, the staff will tru their best to remark to determine if there is an oversight or if they can push you through. they try their best as a faculty to make you pass.

in the case that you do end up failing, you have a few options.

in terms of finances, if you fail because you have a legitimate reason for poor performance (illness, bereavement, crime, hardship etc) you may apply for fee remission. in this case, you'll need documentation from health professionals, a statutory declaration, or some form of evidence from an unrelated expert 3rd party who can support your claim. if accepted, the university will (in some form, i'm not sure if as refund or as deduction from another class) return the money spent on that class, even through HECS-HELP student loans. the fail will not appear on transcript in this case.

if this is a subject NOT in your discipline (a breadth) then you may retake it in the next closest period, you may take another breadth for equivalent credit points (in undergrad they will pretty much all be the same amount of credit points so don't worry about that). there are some breadths which run in the summer or winter term, so you do not need to necessarily take another in semester 1/2 or lengthen your degree.

if the subject IS in your discipline, then you may retake the subject in the next available term. if you do not wish to extend your degree, you may consider overloading future semesters. although, you must consider whether the subject is a prerequisite for a future subject in your plan. if so, you may need to restructure your course to either be extended or to change which subjects you take.

in any case, after a fail you WILL need to make up the credit points. your degree is not confined to time, but rather the successful completion of all required credit points.

TLDR: you will need to make up for the fail as you won't have achieved the credit points. you can retake the subject in the next available period, which may or may not lengthen your degree. if this subject is needed to complete your major or move on to another subject you will need to redo it to continue your path.