Beware “loss of use” claim not covered by insurance.
We bought all the insurance cover they came up with. 2 days in we got a flat tyre. They told us we could not get the tyre fixed, they had to give us another car and so they swapped it for us in the next town we went to.
After the end of the rental we received an email from their Damage Department saying we owed them for the loss of rental on the days they kept the car off the road to get the tyre fixed. (3 days to fix a tyre??)
Any damage it seems will incur this charge, so even if you have paid for all insurance offered you will not be safe from this scam.
They threatened that if we don’t pay it they will blacklist us from Sixt internationally. As if we will ever rent from Sixt again. Still fighting this charge.