I'm certain UWA uses the last 3 years of study (unfortunately I am too familiar with the process haha) Interesting they would tell you otherwise though.Well, when I was investigating this (as my undergrad GPA is rubbish for Med), they confirmed via email they'd only use my postgrad. I might still have the email, but I'd have to search because I asked in about March when I was contemplating grad Med (and then tried a practice GAMSAT and realised lol no!).
"Levels of study included in the GPA calculation (including post graduate study by coursework)
UWA calculates the GPA based on the most recent three years of full time or equivalent (FTE) study excluding any exemptions, credit or advanced standing. As an example, three years of full time or equivalent study at UWA is 144 credit points, at Curtin it is 600 credit points, at ECU it is 360 credit points, at Murdoch it is 72 credit points and so on. " GPA Calculation > Faculty of Health and Medical Sciences: The University of Western Australia
Unless you have a PhD, in which case your GPA is automatically 7.