general problems of the 2005 Toyota Scion Xa

In June 2009 I was coasting into my parking space at work, when all of a sudden my 2005 Toyota Scion Xa accelerated, drove over a parking bumper, plowed into a small tree and drove into a brick wall. The brakes failed and were totally useless. I had my car towed, to the Toyota dealership, where I purchased my car. I reported this incident to the Toyota dealership and was informed that they never heard of any problems, like my own, with the scion. The repair shop told me that I must have hit the gas pedal instead of the brakes. They assured me they would look into the problem but unless it happens while they were working on it, they could do nothing. I wrote to Toyota motor sales in torrance, CA in September 2009 describing my concerns and never received a response. Since this incident, there have been several incidents where the engine has raced on its own. Also, very often when the gas pedal is depressed it seems to feel like it is "sticking" and/or not getting the message that it is time to get into gear and go forward.