Did your insurance cover the repair? If so, you might be able to use them as leverage. Most insurance companies will work on behalf of a customer who gets fucked over by the collision department.

My 2010 Highlander was involved in a front-end collision. When Shit Collision, Inc, replaced the plastic bumper they broke the two body panel brackets that held the quarter panels above the wheels to the new bumper. Rather than admit the mistake, suck up the cost as a mistake, and carry on, they told me it’s “supposed to be like that” (i. e. sticking out an inch and a half from the rest of the car’s body).

No matter the amount of bullshit I called on them they wouldn’t budge. So I called my insurance company. After a tense exchange between Manager McNuts and Adjuster Andy, the body shop still said no so I went elsewhere, insurance covered it, and Shit Collision, Inc., is an empty brick building now.

If this was an insurance repair, contact your insurance company. They have policies for when additional repairs are needed afterwards. Tell them it’s something you noticed later. And if it’s anything that could plausibly be related to the accident, they should cover it. It’s possible there is still concealed damage that is putting stress on the light causing it to separate and let moisture in. If your insurance company OKs it, I would let a different body shop handle the repair and check out the previous work.

If you paid out of pocket, you’re probably out of luck at this point.