If you did not pass the exam on the first attempt, and need to purchase a retake exam, then you need to do the following before attempting to take the exam again:
The retake fee is $17.60 (Australia). To purchase the retake, sign on to My Courses.
Instead of clicking the course title to go into the course, click on the Show Details link below it. You will find a Purchase Retest button below the provided information.
Click the Purchase Retake button, and order the retake online. You will be able to take the retake exam after you receive the retake key code (two business days after purchase). This new key code will come via e-mail to you.