Handle clients rude by putting the phone down while thry were explaining a incident

It was more or less 20:00 and I knew I am tired and asked a friend to help me by going with one car to drop a disabled friend in Somerset West. We left het car in front of the Shell garage, looking all around to see where we may park. There were several signs except for in front of the shop. We decided that it means that we could park her car there and get it when we come back. When we came there by more or less 22:00 the car was clamped. We tried to explain to the security guard. He phone the manager and hand the phone over to my friend. She was, very politely trying to tell our side.. when the manager just put down the phone on the other side. The manager also said there were signs at the entrance of the garage. I took photo's of the entrance and in front of the shop.... NO SIGNS AT ALL! Needles to say we had to pay R250 just to get home.