I read through the summer website and found out that the full fees only apply if you take any courses from the Australian Business School.
"This means that even if you are a Commonwealth Supported student in your program, enrolment in Business School courses over Summer Term will attract Full Fee tuition charges,*not*the subsidised Student Contribution amounts charged under Commonwealth Support."
"Enrolment in courses other than those offered by the Business School will remain under your current tuition status. This means that if you are Commonwealth supported, you will be charged the 2015 Student Contribution rates for Summer Term.* If you are Full Fee Paying, you will be charged the 2015 Full Fee tuition rates."