Car rental conflict

Hello dear friends! I'm writing this post to find out if I can manage a conflict with a car rental company and get my money back from them. Please let me know if it's possible and what I can do in this situation.

I had booked a car with XYZ for four days, intending to travel to Dresden and the Czech Republic. Upon arrival, we were informed that we would be provided with a X. However, when we mentioned our plan to cross the border into the Czech Republic, the manager told us this was not possible with a German-registered car.

This was the point where the conflict began. I had initially booked a Y, a car manufactured in Spain, which should have been eligible for cross-border travel. The substitution of the X was not requested by us, but was made by the rental center. When I raised this with the manager, he offered us a much smaller vehicle with a manual transmission, despite our reservation being for an automatic vehicle, and the fact that we were traveling with four people.

We then asked for a few minutes to reconsider our travel plans, deciding to remain in Germany and not cross the border. However, when I informed the manager of this, he rudely refused to provide us with the original car, stating that the automatic vehicle we had reserved had already been given to another customer. I find this completely unacceptable, as the substitution was neither our choice nor our fault.

Despite my attempts to find a compromise by requesting any available automatic car, the manager refused to offer any solution. Throughout this interaction, he was impolite and rude. To make matters worse, when I asked him to escalate the matter to a supervisor or branch manager, he responded sarcastically and wasted time instead of attempting to resolve the issue.

The situation escalated further when, as we were preparing to leave, the manager suggested we take our business to another rental company, saying he no longer wanted to rent us a car. As a result of this entire ordeal, we not only lost the prepaid money for the rental, but we also missed our first day’s booking in Dresden.

Now, I am requesting a full reimbursement of the prepaid amount for the car rental, as well as compensation for the missed booking due to the company manager's refusal to fulfill the rental agreement and the unprofessional conduct we experienced.

This is what happened, and I'm looking forward to hearing from you any pieces of advice. I would really appreciate any ideas. Thank you in advance!