I am not sure how Sixt and rentalcars.com collaborate but it was a terrible experience and I dont recommend it to anyone. I have now overpaid, rentalcars.com put loads of money in its pocket for absolutely nothing (Sixt confirmed when picking up the car that no insurance was included in the package) and have a terrible/obnoxious customer services team. Never again.
Huge scam and do not get me started about this Philip guy from customer services whom I had to endure over the phone when trying to understand what amounts they charged me extra for.
In May 2018 I go online to reserve a car with Sixt via rentalcars.com and was debited immediately 570 from my account. I picked up the car at train station on 14th July at Sixt counter and first i cannot even take the car because the reservation name does not match the card name my wife and I want to use for the guarantee. We are there with 2 kids and my wife is pregnant but nothing can be done until we have to give a corporate card as only solution we ourselves came up with.
A few weeks later I get the invoice from Sixt telling me that we have to pay an extra 74 for the car seats on top of voucher of 470 - the question is where did the 100 go from the upfront payment? I call Sixt to clarify but they do not care and tell me to go to rentalcars.com. I call them and Philip answers telling me that the IT system is down. I ask about pricing policy but he says each customer is different (so they can scam them i start thinking) and after waiting 30 minutes the IT system is back up and he tells me that the difference is for an insurance I paid straight to them and not Sixt. In his answer he tells me that my quoted 25% overpayment from earlier was wrong - the nerve of this guy!