Thrifty Car Rental is not honest about where you can drop of different classes of vehicles

I had booked a car vs Thrifty Head Office to rent, and they had told me, George Airport don't handle Class P (Cheapest) cars. The result was that I had to rent a class A car, that is more expensive than a class P car. I had landed in Cape Town, where I had picked up the car, and they had told me George handle class P cars. When I had handed my car in at George they had told me they handle class P cars I had directly lodge a complaint at their customer care and was told they will get back to me not later than 2 days after our conversation. Nobody came back to me, and I had phoned again, but nobody had answered at the customer care and the switch board operator had taken a message and had said that customer care will get back to me. Nobody came back to me and I had to phone them again. This time I was able to get thru to customer care and the representative had said he see my point in but he cant do anything. I had then asked to speak to his supervisor, but was told she was not currently available. I had then said if she don't phone me back in the next hour or two, I shall lodge a complaint via Hello Peter. This is why I'm lodging this complaint. I wanted to get the price difference between the 2 classes vehicles paid back to me. (Rental Agreement ***)