Viva fail

I recently bought a Holden Viva Wagon 2008 model, which was a stretch to the budget, but with having two toddlers I needed a reliable new car. What I got was an A-Grade LEMON! The car has needed to be fixed several times for a number of different reasons, including a complete transmission replacement after only six weeks. I am getting the run around from the dealer, and after several complaints and phone calls I am getting nowhere. What can I do? I have recently been in contact with Consumer Affairs Victoria, who have advised me that I am well within my rights to ask for either a refund or exchange. Do you think this is the next best step?