[RKP-M6]

Please forgive me if i posted in the wrong area.

Currently i have a ml350 2006, and I have taken it into the service center about 4 or 5 times for the exact same issue. long story short my windshield wipers stop working at random during rain storms, and the rain sensor at random will not work either during storms. living in the pacific northwest this is a huge problem, and a big safety issue. My dealer keeps saying we can fix it, but this is obviously not true. I feel I should get my money back for the car, it is still under warranty, and I dont feel safe driving it in rain or in dry weather, because who knows what else could go wrong. Does anyone know what is the next step for me? i talked to the service manager at my dealer and he just kept insisting it will be fixed (which I know it wont be). Please help me...I am kind of lost as to what to do next. Thanks.

CP