Airport Parking failure

After paying the deposit and confirming the procedure to be followed beforehand, no one from Express Airport Parking could be found at the airport to collect my car. I called from 04:00 until before departure at 06:00 and no one answered either of the two telephone numbers. I had to use casual parking for 5 days at considerable cost. Now they are simply not owning up. Their failure cost me more than R600 and a lot of inconvenience. They simply claim that their staff were on site, and did not hear the telephones...