Worst Rental Company Ever

I rented a vehicle from Dollar Thrifty from the 04 March 2018 to 11 March 2018. The online booking process seemed easy, I took the super waiver and selected that I wanted 200km per day usage. When i arrived at OR Thambo to collect the car I found that the super waver was not selected. I queried this and they said that they do not receive this information via the online booking and had to add it manually however they saw i paid for it. On the 11th of March when I went to return the vehicle i filled it up and dropped the car off. later they deducted money from my credit card. i called and spoke with rowan and he said it was for fuel. i explained that the car was full when i returned and he asked me to send the slips which i did. since then i cant not get hold of him or anyone at dollar thrifty. i have called the customer service number 4 times today and i can not get through, it keeps telling me an error has occurred. I cant claim this back from my work as i do not have an invoice as yet as this query is still pending.