2002 LAND ROVER RANGE ROVER Steering Problems

WHILE DRIVING AT 60 MPH ON THE MARYLAND 495 BELTWAY (HIGHWAY) MY VEHICLE (STEERING WHEEL, BODY OF VEHICLE, MYSELF, ETC.) JUST STARTED SHAKING VIOLENTLY AND EXTREMELY HARD TO CONTROL. I WAS HORRIFIED AND AT THE SAME TIME I HAD TO LOOK OUT FOR OTHER VEHICLES ON ALL SIDES WHILE I SLOWED DOWN TO 45 MPH. NOW, DOWN THE ROAD AND WITH VERY LIGHT TRAFFIC NEAR, I STARTED INCREASING MY SPEED TO 55-60 TO SEE WHAT WAS WRONG AND AROUND 60 MPH THE VIOLENT SHAKING STARTED. I REDUCED THE SPEED TO 45 MPH. WHILE TRYING TO DIAGNOSE, I STARTED TO INCREASE MY SPEED AND AT 55 MPH I HIT A BUMP IN THE ROAD AND IT STARTED SHAKING VIOLENTLY AGAIN. I'VE TAKEN MY VEHICLE TO THE RR DEALER SEVERAL TIMES FOR SERVICE AND EXPLAINED THE PROBLEM AT THOSE SPEEDS AND WAS TOLD, I JUST NEEDED AN ALIGNMENT. NEEDLESS TO SAY THAT...