Car Accelerates On Its Own problems of the 2007 Lexus GX470

On 8/15/09 I was in my 07/Lexus/gx470/wgn v-8. I had parked in our hospital parking lot where I volunteer. I was moving my vehicle from the w side of the parking lot to the e side of the lot to enter another area of the hospital. My aunt was with me the auxiliary president walked down the sidewalk to meet us. I drove to that area slowly came to a parking space was slowly pulling into the space, a few feet from the sidewalk my car went absolutely wild and crazy, it sound and acted like an angry violent animal, it jumped the sidewalk, I managed to miss a tree that was in its path, it went up a grassy area along the sidewalk headed for the front of the hospital, I threw the car out of gear and it stopped. We were not hurt, the auxiliary president witnessed this as she was walking down the sidewalk. I cannot described to you how I felt, there are no words to describe this horrific experience, my aunt and auxiliary president were also speechless and horrified. I slowly drove home in the vehicle, immediately called Lexus little rock, ar which is where I purchased the car. They told me it had to be the floormat, I checked it and it is secured with gromets,, they told me it had to driver error which I don't think it was, I had my foot on the brake, they said I most probably had it on the gas also. I cannot prove that I did or I didn't, I did not look down,, I was trying to stop the car. The car did dig up sod when it was going crazy along the sidewalk whatever that means. I had roadside take my car in they Lexus checked it out, found nothing wrong. I have driven it since no incidents. My invoice does not show I had a problem, called my dealer last week to voice my concern about all the recalls, ask why sudden acceleration was not documented on invoice, he stammered said well it says your brakes were spongy and grabby, also a complaint ,but that was definitely not why my car was hauled in. Would you please document this and do you have any advice.