[zx10guy]

Don't mean to pile on, but you should have never let things go when the problem with the headlight occurred at the pickup at the dealership. It's a well known and documented problem that these headlights are highly sensitive with moisture penetrations. You have just cause to pin them as being responsible as they were messing with the headlights and ran your car through their car wash. All of this is clear evidence they are responsible. And one of the rare cases of having the dealer wash your car being of benefit. Because I always tell my dealer not to wash my car. The last time they did it, there were faint scratch marks on the hood. Had I been in your situation, I would have had a tougher time proving they were responsible.

And the other thing you did which added to the misery was leaving the headlight alone after knowing there was moisture penetration and then proceeding to wash your car yourself. Should have gotten to the bottom of the moisture issue before subjecting your car to more water.