Expo Parking

I booked expo parking for the Chris Brown event and paid for it. The day of the concert we were told that the expo parking has reached capacity and we need to use the free parking. I have since tried getting in contact with ticket master who has sent me from pillar to post with no resolution. I am requesting a refund for a service that was not rendered to me and ticketmaster customer agents are of no help and provided me with the same automated feedback.