Claimed after hitting a rock at the bottom of my car

Claimed after hitting a rock at the bottom of my car. They took my car for over 2 month. Didn't fix the problem, instead said it's not related to the incident. I recorded a video 1-2 days after the incident. Had witnesses in my car. After receiving my car back, I took it in to have it looked at. According to the mechanic it is totally possible for the knocking (hy****ic lifters) to have been damaged due to the knock underneath my car.