I found that the left rear end of front undersheild pastic sheet bent down and is loose.

I thought the bolt was not tightened, but it seems that the metal part into which bolt goes has been detached from the body.

Is it expensive to repair this?

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1992 300D 2.5 turbo diesel. 319 k miles.
124.128 chassis, 602.962 engine, 722.418 tranny.