Speed Control Linkage problems of the 2000 Nissan Xterra

I was driving on the freeway at approximately 65mph. When encountering slower moving traffic I attempted to slow down by applying my brakes. The vehcile would not slow down. I tried again it would not slow down. I steered the vehicle to the side of the freeway. I placed the car in neutral and the engine roared the rpm indicator was in the red zone and wold not come down as the vehicle continued down the berm of the freeway. I turned off the ignition and the vehcile eventually slowed to a stop. Trembling I called my father, when he arrived he checked under the hood and discovered that the throttle assembly controlling the fuel injection system jammed and locked u the vehicle a 2000 Nissan exterra was taken to the boardman, ohio Nissan dealer. They did not react too concerned regarding my narrow escape with possible injury or death and greased the assembly and said it should be okay. I wanted the assembly replaced they claimed it did not rquire replacement. I thought it best that I report this incident to your agency.