gas pedal was stuck and the car was keep accelerating

While I was driving at 9:10pm, the car started accelerating without my foot. I put my foot on the brake pedal. I stepped very hard and started slowing down. If I loosen the pedal, the car started accelerating. All the sudden I heard popping sound and started slowing down. I think that was the sound of the gas pedal released. At 9:15pm, the gas pedal was stuck again. The acceleration was full and reached to the 80 miles very quickly. I stepped the break pedal slowly but very hard then started slowing down. I tried to pull my car on the side of the road but could not stop. So, I put the gear into "N". I hard the gas was still going. As I stepped on the gas pedal one more time, the pedal was released, so I could stop. As the area do not have good phone connections any way, I drove the car again, slowly, to the dealer and left the car there. It was extremely dangerous. If the driver was my wife, she probably had an accident. If the road was icy, if deer came out, if that was in city area or in our drive way, I had very bad accident.

We bought this car in the middle of August. Tire pressure ramp it always on, but everything else was great until this. I would never want to drive the same car even after a repair. It was awful and can not trust anymore.

Update from Dec 17, 2015: According to the dealer, the pedal was stuck to the additional I added. So, I removed the mattress.