Windshield Wiper/washer problems of the 1997 Mitsubishi Mirage

Every time it rains, I must use windshield wipers, but they fail to work at all sometimes--about 50% of the attempts, and do not work well enough the other 50% of the time. I have discovered that I can stop the car, leaving the car on, and 'exercise' the wipers to get them to work better. I took the car in to the dealership, but they were unsuccessful with pinpointing the problem. The wipers happened to have begun working, as is the commom occurrence; so that was good enough for them. It is extremely fightening to be driving along the interstate and have the wipers stop working! that has happened many time--including on trips. The dealership was willing to try a $90. 00 switch and if that did not work , they would have replaced the motor for over $300. 00 more. They refused to guarantee locating and fixing the problem for that amount of money--plus labor, of course. So, the problem just remains. I have estimated the date that the problem first began because I had been dealing with it since the beginning of having this car. That date is an estimated time of when I took the car to the dealership about this problem. As well, the number of occurrences is an estimate. I don't know how many times it has occurred. It occurs every time I use the wiper system. I asked the dealership if others had reported problems with wiper systems of Mitsubishi Mirages; I received no answer. I would like to receive help in finding someone who can repair this problem. I wonder if the dealership is required to repair a problem such as this. Would a wiper system failure problem be considered a serious problem? I hope so since being able to see is vital to the driving situation. I know that whenever the wipers stop, I have to find a way to pull off the road without causing an accident in the process of it and despite the fact that I can no longer see the road at all. If your department can help me, please call or email me. Thank you for hearing my issue.