Holden Astra 2005: Engine and transmission problems

You might remember that I contacted you with regard to a problem with the engine in my 2005 Holden Astra, which broke a timing belt and caused severe internal damage to the engine. Holden ended up coming to the party on the engine, paying 66 per cent of the repair cost. Well, I have now had a problem with the auto transmission, which has blown up. After much argument this time Holden has again offered to pay 66 per cent of the cost. Is it possible to have so much bad luck with a car that has only done 66,000 km. I would really like some legal advice, but don't know where to start. Would it be the ACCC?