The location for returning the car at Cologne station is not clearly marked, and the navigation on the car rental app is also incorrect. It took a lot of time to find the return location.

The rental company proposed two solutions: first, switch to another car and pay an additional 61 Euros; second, cancel the order with no refund. I requested an automatic car, but it was denied. I called the customer service in my country for help. They assisted by submitting a request and advised me to take photos for evidence.

Acceptable

The car rental location is inside the train station, and all the rental companies are together. It's very fast! There is a lounge downstairs to store luggage. To pick up the car, you need to go to the above-ground parking lot across the street. The staff will give you a map, it's pretty easy to find. Take the elevator up, and the elevator has a password, which is on the parking ticket given by the staff.

It's a bit of a walk from the train station, and you have to cross the street, but the front desk provided clear directions. You pick up the car yourself using the parking ticket given by the front desk at the exit. There aren't many gas stations nearby, so I used GPS to find one near another store to refuel. For returning the car, drive to the ground floor of the parking lot, and hand over the car, keys, and documents. There's no paperwork or handover documents needed.