Rentalcars.com a scam

On the 16th of September I booked a car through rentalcars.com. They arranged the car with Tempest at East London Airport (SOUTH AFRICA) which was closed and was referred to Eaurope Car who informed me that they could not capture the Voucher. I called rentalcars.com immediately asking them to rebook the car with another service provider but they demanded more money on top of thecdepisit I paid which I refused to pay but asked for a refund. Today they are telling me they can't refund me because I never went to the airport counter to collect the car. This is daylight robbery.