I have used http://www.amigoautos.com/ . The useful thing about them is that you can book online with no payment, and then go back in a month or so and get a new quote. If that quote is better, just cancel the old booking free of charge.
Also my keyholders Aidan & Mandy Enterprises based on HR are a legally registered car hire company offering cars for hire at Hacienda Riquelme Golf Resort only. http://aidanandmandy.com/CarHire.aspx
Steve