rentalcars.com The way to swindle people on the net Manchester United KIngdom Internet

I've rent a car through this internet company ( rentalcars.com) 2 hours before I had to get it. I've call the local office and have been told that the car I've booked is not available and the price I've to pay is higher than what has ben booked.

So I requested from this person to cancel my booking and I've been told there is no problem and the payment made by credit card will be refund.

 I've got a mail shortly after this cancellation telling me that the cost of the cancellation will be equivalent to 3 days of rental cost because cancellation was not been done at least 48 hrs before I've to get the car and my account will be credited after 7 days ...

I've tried everything to explain by mail it was impossible to cancel 48 hours earlier because the booking has been made only 2 hours before the cancellation. i've only received stupid replies and have not been refunded. 

Once again using internet is very dangerous with not serious suppliers.