Steering Failed problems of the 2007 Chevrolet Silverado 1500

My 2007 crew cab Chevrolet Silverado 1500 was purchased on 11/27/06 and it has approximately 65,000 miles on the odometer as of 12/22/10. The steering is making a clunking noise and jerks when turned to the left while moving in forward or reverse. This same incident occurred at around 20,000 miles in the 2004 Chevrolet silverado that I purchased from the same dealer prior to the purchase of this 2007 Chevrolet Silverado 1500. At the first sign of steering failure with both vehicles, I took the vehicle directly to the dealer. The steering malfunction in the 2004 Chevrolet was fixed free of charge. When I purchased this vehicle (2007 Chevrolet Silverado 1500) I was informed by the same dealer that I wanted exactly the same warranty and was told that it had been supplied. I took my vehicle to the dealer as I had done previously. On 12/22/10, I was informed that I would have to bring my truck back at 0830 on the morning of 12/23/10 and that I would be required to pay a CO-pay of $100. I am certainly no mechanic, but if the steering is failing, would it not be a safety hazard to put the driver back on the road in this vehicle? according to the complaints that I have read on your site, this is a recurring problem. For me, this is second Chevrolet silverado in which this same problem has occurred. I do not remember exactly which parts the dealer replaced in my first vehicle, but the beginning symptoms of this steering malfunction are the same as those that occurred with my 2004 silverado. What frustrates me about this situation is that the failure seems to occur quite frequently in the Chevrolet silverado. Should they not be held to some standard of at least replacing poorly designed steering parts at no charge?.