Hertz hasn't refunded my deposit

My insurance company provided a courtesy vehicle while mine was being repaired. The rental company was Hertz and I was required to pay a cash deposit of R1 500. The deposit was to be refunded after the deduction of R65 for admin and any petrol required. I received an invoice confirming that R1 435 was due to me as I had filled the tank prior to returning the vehicle. The vehicle was returned on the 22 April 2022 and after numerous attempts, I still have not been refunded my deposit.