I took my car to auto shop for oil change. I found a dent below rubber strip on the drive side front door after I came back and paid for everything. When I opened the door, I can clearly hear scratching sound and feeling the door rubbing against the car body. I talked to the manager, and he asked the mechanics but they denied everything and they said it's there before the car got to the auto shop. They are clearly lying because I didn't feel or hear anything today before I left the car for the auto shop to do oil change.
I called my car insurance, and they said they don't cover and they suggested small claim court. I took photos of the damage, and the auto shop manager took photo of my VIN # (I don't know why). I called the police station and they said police report won't help if it's a civil case, so I didn't ask them to come out.
What should I do next? Manager refused to fix it, he said that it's not a body shop. What's the chance of winning a small claim case against it? I don't have witness. This car is almost 19 years old. Any suggestions?