Missed a funeral because lack of professionalism

My parents and I arrived in Johannesburg an hour ago, and because of the horrible service at Tempest Car Hire at the airport we have now missed the funeral which we came to attend. My mother had called them on Saturday after we found out about the death of a loved one. The employee who took her call and helped her to book the call had said that we would definitely be paying them R365 with a down payment of R1670 which would later be refunded. No problem there as my mom had confirmed this with the woman 3 times before finalising the car we were to hire. We arrived at the place and were ready with our money to pay and get going as fast as we could. We were then informed that we would have to pay a further R5000 cash which we were not aware of at all. This was highly unprofessional as we were promised one amount and then given a higher amount once we reached there. We could not afford to come up with R5000 cash in such a short period of time and were forced to go looking at other options until we finally managed to hire a lift from Bolt. If Tempest Hire had been clear about the money in the first place instead of promising such a low amount we would not have missed the funeral. I am very unimpressed and will never even consider using them ever again.