Similar thing happened to me a while ago. I was in Tesco and was just walking back to my car when I saw a car pull into the space next to mine. A femal passanger got out of the back seat and clearly slammed her door into my car; she even caught my eye as she did so but didn't realise, at first, that it was my car. She started walking away and I called her back to point out the damage. She claimed it wasn't her and her partner opened the door to prove it - the dent and chip was just below where the door touched my car. I reasoned that if they were both sitting in the car at the time, then the door would have hit slightly lower. She then went off on a rant about how she only weighed 8 stone and there was no way she'd may the car dip that much. They walked off and I photographed my car, theirs and took their registration number. Nothing came of it. It wasn't worth claiming for. In any case, my car was keyed a few months later and the lovely men at the body shop fixed the dent for me at the same time for free...yessss! It's so annoying. Just a thought...do Morrison's have CCTV in their car parks? If you report it to the police, can they look at the CCTV for evidence?