2001 BMW Z3

DOORLOCK CYLINDER ASSEMBLY INSIDE DOOR BREAKS, CAUSING LOCK CYLINDER NOT TO BE HELD IN PLACE & WHEN KEY IS INSERTED IN LOCK CYLINDER THE WHOLE LOCK CYLINDER JUST TURNS WITH THE KEY. MAKING IT IMPOSSIBLE TO LOCK OR UNLOCK THE DOOR. I'M EXPERIENCING THIS PROBLEM WITH PASSENGER DOOR & THE DRIVERS DOOR IS STARTING TO ACT SLOPPY ALSO. THIS IS A PROBLEM EXPERIENCED BY MANY BMW OWNERS OF DIFFERENT MODELS. BESIDES BEING POORLY DESIGNED IT'S VERY EXPENSIVE TO REPAIR; APPROX. $500 TO $800 PER LOCK...NOTE "THE REPAIR DOES NOT REQUIRE NEW LOCK CYLINDERS, JUST THE HARDWARE THAT HOLD THE CYLINDER INPLACE, BUT THIS HARDWARE IS DIFFICULT TO FIND & THE BMW DEALER IS USUALLY THE ONLY PLACE TO GET IT AT A HIGH COST. I HAVE SEEN DOOR LOCK CYLINDER ASSEMBLY HARDWARE ONLINE FOR UNDER $20.00; BUT BMW CHARGES $100 TO $200." BMW PRIDES ITSELF ON QUALITY. I THINK THEY SHOULD STAND BEHIND THEIR MOUTH! I'VE HAD CARS OVER 40 YEARS OLD. THEY'VE HAD A LOT OF PROBLEMS, BUT DOOR LOCK CYLINDER ASSEMBLIES, NO & IT WOULDN'T HAVE BEEN THIS EXPENSIVE TO FIX! THANK YOU *TR