ProPark America Expresso Parking Damage to car at airport parking garage and denied claim outright without even talking to me. Oakland, California

I parked at Expresso Parking lot by the Oakland airport for five days.  When they drove my car up I saw from about 25 feet away what appeared to be a dent.  As I got closer it was clear that someone had dented the rear driver side door -- looked like another car door was slammed into it.  I immediately reported it to the attendant and then spoke to their manager and filed a claim.  I was told someone would contact me within a few days.

I did not hear back and called and emailed two weeks later.  Again I was told someone would contact me shortly.  No response.  I called again another week later and was asked to be patient because they were behind and would replay as soon as possible.  Then I got a letter denying any responsibility for the dent and saying that I needed to use my own collision or comprehensive insurance coverage.