@Mal-and-Sim0 Did you search the forum for insurance australia? I know I have outlined this topic in several earlier threads.
Surprised GIO ever offered STR insurance - most of the large insurers do not.
I have 2 airbnb apartments on top of me - all part of the same standalone house - so similar situation. I use Ceneta Insurance Services and they sometimes change my insurer each year- they look for the best deal each year, Single premium to cover both my area plus landlord insurance for STR. My current policy with them is HomeBiz Homeshare
It has been going up - a lot since I first started - as most insurance has after all of these weather disasters.
Currently just under three thousand PA.