IN THE PROCESS OF PARKING AT MY SISTER'S HOME, I TOOK MY FOOT OFF THE ACCELERATOR AND STARTED TO BRAKE. THE CAR DID NOT SLOW DOWN. I CONTINUED TO BRAKE, BUT THE CAR KEPT GOING FORWARD WITH INCREASING SPEED. I WAS ABLE TO STEER AND NOT HIT PARKED CARS, BUT WENT INTO THE LAWN HITTING A SET OF CONTRACTOR'S SCAFFOLDING SENDING THEM FLYING INTO THEIR HOUSE AND PATIO. THE CAR FINALLY STOPPED ON TOP OF THEIR WELL HEAD, DESTROYING THE WELL COVER AS WELL AS THE PROTECTIVE PIPE FOR THE WELL HEAD. FURTHER INTERNAL DAMAGE WAS DONE TO THEIR WELL, AS THERE WAS NO RUNNING WATER IN THE HOUSE. A TOW TRUCK HAD TO COME TO LIFT THE CAR OFF THE WELL HEAD TO AVOID ANY FURTHER DAMAGE. I HAD BEEN USING THE CRUISE CONTROL EARLIER IN OUR TRIP, BUT IT WAS NOT ACTIVE AT THE TIME.