Parking at OR Tambo is a RIP-OFF

We parked our car at Parkade 2 at OR Tambo on the 1st April at 6:00 in the morning to fly to Durban and returned and fetched our car at 19:00 the same day - we were charged a wopping R810.00 - we were shocked but just had to pay it - what a rip-off - how is this calculated? - no where on the rate calculator on the net does it come anywhere near to this amount - WHAT A RIP-OFF