My windshield wipers won't turn off. In June, my wipers suddenly stopped working completely. I took it to a Mercedes Dealership and they wanted around $850 for a new wiper arm and wiper motor. Instead, I took it to a smaller mechanic, who specializes in Mercedes and he agreed on the problem and charged $550. A month later the wipers suddenly would NOT turn off. They stay stuck in the slowest wipe mode. I took it back to the mechanic and he said it has NOTHING to do with his previous work and since it has been a month, he will not refund any money. He wants another $400 to order a part to fix it---although he admits that he really is not sure what the problem is. This seems wrong to me. What else could be wrong?