Scheming scammers, but maybe that's the S. Africa way. We were very careful, filmed everything, and they still refused to give us a receipt, or do any damage inspection. The scam is, I believe, if they see you are from another country they wait until you leave the Africa (obviously, since you're dropping off car) then add on a few extra hundred. Nothing you can do and credit card Co's don't care. Only when enough people complain will something get done.
When I turned in our car I actually went to the manager and politely requested a receipt, while filming the request on my smartphone. Wow, that sure made them nervous. Last thing they wanted was a record. Didn't matter, still no receipt (2 months later) and no reply, but only added an extra $50 so it's not worth my time. Filming must have helped.
I'd suggest you film everything so at least you have a record you can sent to credit card company in a dispute.