Couldn't pick up the car at the store. The system forced me to select a car model to submit the form

I had a reservation for Sunday, July 28th. I arrived at the pick-up location in the morning, but the door was locked. I had to make an international call to the customer service and was told that the car rental company is closed on Sundays, but my reservation was still accepted. All our travel plans were arranged; what were we supposed to do? The rental platform suggested checking for other car rental companies nearby, but we were in an unfamiliar place! Finally, we managed to find another company but were told there were no cars available. We were really frustrated, but eventually, we found a car six hours later, which somewhat mitigated the loss.