This company (which is part of Priceline) has lots of terms and conditions which work against you and we have ended up with paying 256 for *nothing* in the end. Here is the story:
On a family trip in Italy, we have made reservation for a car rental from this website in May 2013. We have especially requested a navigation device during reservation to find our way easily around the country.
On 19th of May we went to SicilyByCar desk at Rome Termini Station to pick up our car. We paid the deposit, signed the papers and got the keys. When we arrived at the parking lot to pick up the car, we were told that they have no navigation device available! We had to go back to train station (which is 300m away) and ask the lady at SicilyByCar desk. When we asked why she had not told us that navigation device was not available before and made us go through all the signing papers and paying deposit procedure, she did not have any answer at all! We were really disappointed and frustrated.
The only way to go was cancelling the reservation and renting another car from another dealer. So I called RentalCars.com customer services and was told that I need to pay half of reservation fee as a penalty and that was because the pickup time had passed. But we had not get in the car at all! Just because the pick-up time has passed we were made to pay 256 for nothing, simply nothing! All we get was disappointment and frustration in the middle of our trip. Not to mention the half of day we lost during reservations.
When I have placed a complaint, I got a response a month later, which says this is according to their terms and conditions and they will do nothing about it. The rep's last sentence in the email was:
"We are not in position to refund you the rental price and we now close the matter"
That's all I was able to get back.. (oh, and daily spam emails)
So, STAY AWAY FROM RENTALCARS.COM, if you want to stay stress free.