I took my 2000 S500 to the dealer recently about a problem with my right side mirror light. I was told that the turn signal on my right side mirror is not working because of a problem with the whole mirror assembly, not just the turn light/bulb itself, and since this problem is not fixable I have to replace to whole mirror assembly at more than $400, however, the mirror can be moved around perfectly and I've heard this problem can be fixed by simple replacing the light. Is the dealer wrong about this issue?