Persona Is Leak Prone

I BOUGHT a Proton Persona new in 2004 with a three-year warranty. The vehicle has been well maintained, always serviced by a Proton dealer and has done about 17,500km. Recently an oil leak appeared around the head gasket, which a Proton service person says is a common problem that usually happens about 60,000km. He admits having repaired at least a dozen Protons with the same problem. Most cover the critical kilometres within the warranty period, so repairs are done at no cost to owners. Proton never made an official recall to fix this and vehicles are being repaired as they come in. I have approached Proton twice, but have been knocked back because the vehicle is out of warranty. I've had the head gasket replaced at my cost to prevent any damage to the engine. I am now about to approach Consumer Affairs and would appreciate your suggestions in relation to my case.