Speed Control Cable problems of the 2008 Hyundai Elantra

I was driving my 2008 Hyundai Elantra on the highway and began driving on the exit ramp when the brake was applied the car accelerated to a speed of 85mph. I had both feet on the brake and the car would not stop. I put the car in neutral and it slowed to 20mph. At that point I put the car in park and turned it off. The car was smoking and I could smell something burning. Car was taken to Hyundai dealership where they told me the throttle cable had debris on it and malfunctioned causing the throttle to accelerate to high speed. The car had accelerated twice before but not to such high speeds and would react to the brakes being applied.