Engine problems of the 2007 Volvo XC90

While driving on interstate 40 at 80 mph my car began shaking violently and shut off. It was trailored to the nearest Volvo dealership where it took 3 weeks to repair , 1 week to identify the problem). They found that the valve spring" on the 2007 Volvo Xc90's engine had broken, causing the car to operate on only 4 of its 6 cylinders. This car barely had 2500 miles on it at the time of the failure. The cylinder head of my brand new engine had to be replaced, certainly compromising the resale value of my car, and after 3 weeks in the shop,and $6000 worth of repairs including a rebuilt engine, Volvo will not recompensate me (replacement engine, extended warranty, etc. ). I am extremely upset about this. I purchased a Volvo because it is supposed to be the most dependable and safe car on the road. Instead I have been badly mistaken.