On 3/27,2021, picked up rental car (to get BMW 3 Series),at Sixt Rental Car at Airport, however, prepaid TOTAL PRICE $156.44 online, Reservation #990820****.When I arrived the car allegedly was not available and I was cajoled into an upgrade, which is free to most, I was told it would be an additional $144.00 total. I have the car for one day, was charged and charged a total of $661.95. Legally speaking, misleading and fraudulent practices, and over charging customers and hidden fees are actionable. I am entitled to a $505.51 refund. Otherwise, a complaint will be lodged and a judge will make the decision. Which will certainly cost more, e.g, attorneys fees and the likes. I await your response, without undue delay... User's recommendation: Don't shop with Sixt rental car.