Thanks for the replies

trip.com eventually refunded the booking to me
I had to go through a few agents though and only the manager would do it for me
It was hard convincing them that the MCT was 90 minutes, it isn't published publicly anywhere that I can find
They tried to change the booking but because it was a non-refundable ticket the process was quite convoluted and it was easier to cancel and book a separate ticket, which we did on the Qantas website!