Not too much help but a story about my 2010 camaro involving a rattle in the rear suspension: (wouldnt usually write this but i got nothing to do )
took my then, 6 month old car in to get serviced because of a rattle in rear suspension. I went in to pick it up and they did a service bulletin For a spring isolator and said that fixed the problem. I made it 1/2 mile from the dealer and hit a bump and there it was again. Rattle rattle when i hit a little pothole or slight bump. Soo back to the dealer 3 minutes after i left
I walk into the service writers area and kinda lose my sh!t.
He says “what you want me to do”
Me “i dont know make my brand new car not sound like a giant pile of sh!t”
so once again leave it with them, two days later i find a ride to the dealer and walk in expecting nothing. He slams the paperwork down on the desk and points to something taped to the paperwork
it was a piece of 2b limestone, gravel what ever you want to call it in different areas. it Must have flung of my tire in my shop parking lot and landed in the hollow lower control arm.
And they didn't even charge me for the service call.