Brake Disc Rotor problems of the 2006 Infiniti G35

Routine service of the 2006 Infiniti G35x sedan at 18,000 miles required new front brake pads and rotors at a cost of almost $600. When I questioned the replacement of the brakes, especially the rotors, at this early stage I was told by the dealer this was normal for this model at about 20,000 miles. My research showed that this was a historical problem with this model, the company even extended the warranty to cover front brakes on the 2003-2005 models. Complaint filed with the manufacturer but was told this was considered normal maintenance, there was nothing they could/would do.