Another advantage of doyouspain is that you don't pay anything up front and there is no cancellation fee.
I made a booking in December. Then I went on the website today just to get another quote for the same trip. The price for the same class of car had dropped from 42 to 35 Euros, and I could also get a bigger car for the same money ! The rental remained with Auriga Crown.
So I have now cancelled the original booking with no penalty and rebooked at the better price.
Chris