This is an unfortunate outcome and I'm sorry to hear it. I will say it would be difficult to prove one way or the other after 14 days where the damage originated and it's unlikely you're going to get restitution, even in small claims court without photos of the wheels before the shop touched them or when you picked up the car since it's impossible to determine when the damage occurred.
I parked my car in front of my girlfriend's apartment one night and there was no signage at all but, when I woke up the next day to leave and saw my car gone with a lot of newly placed "Do Not Park - Street Paving!" signs, I eventually picked up the car at the police lot and saw the two wheels on the right side had been dragged against the curb when towed. Similar situation and neither the police or towing company would compensate me. I tried small claims court and the judge said what I said above - "I can't tell when the wheels were damaged so I can't rule against either defendant. Case is dismissed." Not to mention the parking ticket due to parking in a temporary no parking zone which was not refunded because it was the word of the Police (Yeah, the signs were there!) against mine (There were no signs the night before and I would have seen them because there was a sign on the tree where I parked!) Not a good day.