Sixt Rental Car Charged Exorbitant Fuel Cost

Hello,
I rented an Opel Crossland through Yolcu360, a company operating in Turkey, for a trip abroad from December 27, 2023, to January 4, 2024. However, when I arrived at Düsseldorf Airport to pick up the car from Sixt, the representative informed me that they didn't have the Crossland available and offered me an automatic Mini Cooper S instead. Despite my objections, explaining that the Mini Cooper wouldn't accommodate my family and luggage due to our heights and needs, they insisted it was the only option available, so we reluctantly accepted.
Moreover, upon learning about my travel plans to other countries, they charged me an additional fee of around €40 for the visit to another country, on top of the €300 deposit fee.
I had brought along a portable foldable car seat for my child, but the car was so small that I couldn't install it.
After a challenging 8 days, I returned the car with half a tank of fuel. However, the rental attendant informed me that I would be charged a penalty for the half tank, at a rate of €6 per liter. This information was not disclosed in the contract provided in Turkey or communicated to me by the Sixt representative before I took possession of the car. I refused to pay €180 for what amounted to half a tank of gas in a car with an average capacity of 60 liters. Instead, I requested that they calculate the remaining deposit amount based on the average fuel price in Germany after determining the actual amount of missing fuel.
However, the real ordeal began afterward. They claimed a shortage of approximately 25 liters of fuel and charged me €153 for it. Despite reporting the issue to Yolcu360 and corresponding with Sixt in Germany, no resolution was reached. I don't want more people to be deceived by various ads promising advantageous car rentals with Instagram influencers. They charged me €6 per liter for fuel, which costs less than €2 per liter everywhere in Germany, without any signed document or prior agreement. They made me pay more for fuel penalties in 8 days than the rental fee I originally paid. It's truly outrageous!



