Subaru Impreza 2006: Mystery electrical problem

ABOUT a month after buying my new Subaru Impreza it developed, what I believe to be, a minor electrical problem. It doesn't affect the performance of the car, but it is still a problem. The car has been back to Subaru five times with this problem, and it still hasn't been fixed. Subaru does not appear to know what is wrong, and tell me they are testing a vehicle in Sydney. I have made several complaints to the company, but have not heard anything I don't already know since June. I get the feeling they are giving me the runaround, hoping I will eventually forget about it. The after-sales service from Subaru, from my point of view, is pathetic. What are my rights as a customer? What should I do?