Pathetic customer service and unfair refund terms

I booked a car online to collect at OR Tambo International Airport. i had already paid for the booking, the only outstanding payment was the deposit. When i collected the car they swiped for the deposit then they said it didn't go trough but on my banking app it showed that the payment went through. I went to the bank to check and they told me that the payment is not cleared but the deposit is held by the car rental. When i got to the car rental to give them feedback they told me to get proof the bank. I decided to cancel the booking but now the deposit and the car rental fee is still held by them not cleared and they say it will take 5 to 7 working days. I couldn't go to another car rental company for assistance. Then they told me told me that they'll send the customer care an email to accelerate the payment and i've been copied, but that email never reached me. I was helped by