I signed up for Sixt through Kayak. I tried to cancel my reservation, but because it was booked through Kayak, I was unable to cancel on their website, because they said I was supposed to cancel through Kayak. But Kayak also does not assist in canceling. I emailed several times with Sixt, trying to cancel my reservation, and they never canceled it and charged me the full fee. I will not be using Kayak nor Sixt ever again for renting cars.