RentalCars.com Priceline Pre-paid for a car rental but was not issued a car Internet

I prepaid for a car with rentalcars.com (150usd). When I went to their supplier (Dollar Car Rental in Dubai Airport), the supplier would not issue me the car. When I was at the car rental station, they promised a refund, but now they changed their mind and decided to keep the money. 

In the terms and conditions it states that they need a "Mastercard or Visa Credit Card" for the payment of the security deposit.  (1) I provided the first card - but some error occurred (connection or other).

(2) I then proceeded to provide another Mastercard, but they refused to try it since it was not "embosed". (3) I then even offered my companion Credit Card (which is embosed) but they refused to use it since the booking is under my name. When I requested to change the booking name, they doubled the price. 

I finally offered cash - but that too was not acceptable to them.