Car Accelerates On Its Own problems of the 2012 Honda FIT

My vehicle suddenly accelerated to a very rapid speed. I had just started up the car and was reversing out of the garage when the vehicle accelerated. I attempted to stop but was unable to do so. Then the car suddenly returned to normal.

This was the first of two incidents of sudden acceleration. Both times parking the car and giving it a little gas to ease into a space the car took off at high rate of speed; the first time, almost crashing into my garage door and the second time jumping a sidewalk and almost hitting a metal hand rail. I took it to Honda dealership and they said they could find nothing wrong, and said I must have hit both brake and accelerator at same time. However, since my foot is too small to be able to do that, and I was driving barefoot at the time, I am positive that was not what happened. After receiving car back, I checked and was unable to place my foot on both pedals at the same time.