I have used carjet 5 or 6 times in the last 12 months , only in Greece. I have had no problems at all with the process. I dont take their insurance and I google the car rental companies that they are promoting. Whilst I look for cheapest I dont take it if the actual rental company has bad reviews. I have not paid double, not been charged twice, I haven't had a problem with fuel payments (after rental), nor charges for scratches. The deposit has been reversed within 3 or 4 days. I wonder where all the bad service is. It looks like Spain and Portugal aren't good.