Shoddy BMW dealer

I recently purchased a $60,000 Premium Selection BMW from interstate. When it arrived it hadn't been cleaned inside, there were lolly wrappers in ashtrays and sand under the mats, the sound system wasn't working and there was a number of obvious faults with it. After he inspected it the mechanic said it would need a new windscreen, new rear tyres, and he noted 14 other faults. I booked the car in at a BMW dealership in Melbourne, but had to wait for approval for the repairs from the Gold Coast dealership, which took approximately three months and there was still no approval for the windscreen or tyres even though they were deemed to be unroadworthy. BMW apologized on behalf of the dealership and said they would note the issues I had raised, but that it was up to me to contact the dealership to sort out the outstanding roadworthy issues. Eventually the dealer's service manager apologized for the issues I had with the vehicle, but said it was roadworthy when it left the dealership as the tyres had at least 1mm of tread and were confident I would have got a 1000 km out of the vehicle, and that the windscreen was replaced in March when the car had the 100 point inspection and he couldn't understand how it was scratched. How can I take this further, as this is a disgrace?