Defective TVs from Mitsubishi

In 2005, I bought this Mitsubishi TV from Fry's electronics in Fishers, IN. The TV was financed from Mitsubishi's diamond finance at $4000. In the past 4 years I have changed 3 lamps. I am on the third lamp and now the green light blinks constantly. I called a tech from an authorized service station, he charged me $100 to come to my home and within 5 minutes gave me a quote of $700 to repair the DM Board. Going online, I can see that this is a repeatitive problem on this model. Mitsubishi has zero customer service. How do we get the manufacturer to provide assistance ?