I purchased a used car from a dealer in NSW in late December 2014. Since the purchase, I have attempted to repair a major problem with the car that renders the vehicle undriveable. The vehicle leaks fumes into the cab and makes occupants ill.The vehicle has been to two registered repair house for a total of 5 visits. The problem has been diagnosed as irreparable This outcome has just come to light after constant attempts to repair the problem from the initial purchase.The Dealer was of no real help and abrasive in the first instance. Believing the problem could be remedied, I continued to try to find and repair the problem at my cost. During the course of seeking a repair the vehicle ran out of warranty. From the day of purchase to this point in time the vehicle has been emitting toxic fumes making undriveable. I have a paper trail of correspondence and invoices from the outset. The vehicle cost $49000.00. I believe the dealer new of the problem prior to sale. The vehicle cannot be used,or repaired. What can I do under Australian consumer law?