Exterior Rearview Mirror problems of the 1996 Lincoln Continental

Inside rearview automatic day/night mirror in my 1996 Continental has stopped dimming. There is a spot approximately in the upper right middle of the mirror that does dim as it should. As such, when a car comes up from behind (especially when they have brights on), it blinds me and decreases my "night vision. " not only is this an annoyance, but it is also a safety issue. I have contacted the dealership and they said there is not a TSB or warranty on it. It does cost $500. 00. I have e-mailed the company that makes the mirror (donnelly corp. ) but they have not returned my request for additional information on repair, warranty or replacement. I further understand that this may be a "common" problem with 1996 and 1997 conti. . Any assistance in this matter would be greatly appreciated. Thank you. .

The rear view mirror and side view mirror contained film which resulted in poor visibility.