2001 Mercury Marquis WINDSHIELD WIPER MOTOR

I HAVE HAD THIS CAR APPROXIMATELY 9 YEARS. OVER THAT TIME PERIOD I HAVE HAD TO REPLACE THE WINDSHIELD WIPER MOTOR 5 TIMES. IS THIS NORMAL. THE SECOND PART OF THE QUESTIONIS THE LAST TIME IT WAS REPLACED (SEPT, 2009), I HAVE HAD PROBLEMS WITH THE REPLACEMENT. I HAVE HAD TO RETURN THE CAR FOR ADJUSTMENTS. THE LAST TIME I WENT BACK WAS NOVEMBER, 2009 WHERE THEY TOLD ME THAT THE MOTOR WAS FINE. THE 379.00 BUTTON THAT OPERATES THE WINDSHIELD WIPERS HAS TO BE REPLACED. IS THIS POSSIBLE? MIND YOU I HAVE PAID WELL OVER 200.00 TO REPLACE THE MOTOR