BMW will tell you they are not defective. Fact is they are a poor design. Cable actuated lifters are smoother when they work, but prone to failure, especially if not used. To keep failures to a minimum wind the window down at least 2-3 times a week. This will help prevent the cable from getting a kink where the wheels are and cause the cable to jump and fail.

As for the window getting stuck up, that is probably the limit switch. Manually move the window motor and it should release the limit switch and window function will return to normal.