Cancelled and refused refund

Booked to visit Melbourne from Perth for the weekend from 30/06/23 to 03/07/23. Cancelled on 6 hours notice due to staffing shortages. The only alternatives they offered where taking 12+ hours starting on the Saturday morning to arrive Saturday night/Sunday morning. I was due to be flying back a day later with Virgin.

They are refusing to refund me, for what amounts to $650 for the return trip. I am in the process of drafting my reply to them stating Australian Consumer Law. Is anyone able to advise on that??

Australia-Melbourne - Tullamarine