Suspension Noise problems of the 2007 Nissan Altima

As I was driving home from work I noticed a noise in the rear of my vehicle. I made an appointment to have it looked at and it was said to me that my rear shocks are bad and that they had seized into the knuckle and were rusted. I then proceeded to contact Nissan north America to see if they would help out with this issue due to the vehicle only having 42000 miles. They told me that because I had an extended warranty and it was not Nissan's, and because it was not in the factory warranty that it was not their problem. I feel that this is a safety concern because the vehicle is very well maintained and there was a recall on the rear sway bar which could have affect on the rear suspension. They did not feel that my reasoning for requesting assistance was valid and I do not feel safe driving a vehicle that could potentially fall apart while driving.