2002 Volkswagen Passat Steering Problems

THERE IS A MILD TO SEVERE SHAKING IN THE STEERING WHEEL OF MY 2002 VOLKSWAGEN PASSAT 1.8 TURBO 4 DOOR SEDAN. I HAVE HAD THE VEHICAL AT THE DEALERSHIP 5 TIMES AND THEY HAVE YET TO DETERMINE WHAT THE CAUSE IS. THE DEALERSHIP HAS HAD A REPRESENTATIVE FROM VOLKSWAGEN AT THEIR FACILITY ON AT LEAST TWO OCCATIONS AND HAVE PERFORMED A NUMBER OF TEST AND ADJUSTMENTS INCLUDING A FOUR WHEEL ALIGNMENT AND DRAINING THE POWER STEARING FLUID AND REFILLING IT. TO THIS DAY THEY ARE STILL UNABLE TO DETERMINE WHAT THE CAUSE OF THIS ISSUE IS. THE DEALERSHIP HAS TOLD ME THAT THEY HAVE EXCEEDED THEIR KNOWLEDGE ON THIS MATTER AND HAVE ASKED VOLKSWAGEN TO TAKE OVER. VOLKSWAGEN HAS TOLD THE DEALERSHIP THAT THEY WILL NOT BE AVAILABLE UNTIL AT LEAST MARCH 2003. HOWEVER THERE IS NO GUARANTEE THAT THEY WILL BE AVAILABLE THEN EITHER.