While parallel parking in a parking structure; my car accelerated full throttle backing up hitting the back wall ; then I tried going forward to straighten the car up, it accelerated full throttle forward hitting the front wall. I had an doctors appt. there and decided to still straighten car and I said if it goes full throttle again I would immediately put the car in neutral and turn the car off, which I did. Each time the car went full throttle I hit the brake pedal as hard as I can push. Leaving the car I tried locking the car with my key fob, it wouldn't lock or turn off the headlights, it caused the horn to keep beeping for no reason.