wipers seem to work the same any position on switch never stop in park position

Hello, The issue may be in the switch used to turn the wipers on and off, the steering column, or, if the wipers are controlled by an ECU, the ECU could have a fault associated. This will require diagnosis, and I advise that you use an auto electrician, or a certified European/German vehicle specialist. See below for certified repair facilities in your area, and see if you can find someone with factory BMW training. http://repairpal.com/bmw-within-10-miles-of-scotland-neck-north-carolina-27874