Rentalcars robbing customers of their money

Book a car with rentalcars.com Reservation number ***, R1900 taken from my credit card however when i went to fetch the car from the their rental outlent partner thrifty i couldnt not given the car as they said i had a lower than required credit score and advised me to ask for a refund from rentalcars.com as i had booked with them. Rentalcars.com is refusing to refund me the money and referring to cancelation policy , however i never canceled the rental. Thrifty person advised me to contact rentalcars on tuesday as monday was a public holiday and my rental was on saturday.