America Car Rental review: $300 refund & rude attitude of agent in Texas

I am writing to formally express my concern and disappointment regarding my recent car rental experience.
The car was picked up on September 25th and was scheduled to be returned on September 27th. Unfortunately, what should have been a straightforward rental experience became extremely concerning because of the conduct of the agent at the rental location.
During the pickup process, the agent became disrespectful toward my uncle after we declined to purchase additional products and services she was trying to sell us. We felt uncomfortable with the way we were treated simply because we chose not to purchase these additional items.
When we returned the vehicle on September 27th, we brought it back to the same location where we had picked it up. The agent did not inspect the vehicle with us or point out any damage, cleanliness issue, parking violation, or other problem. Instead, she simply told us to leave and quickly arranged for the driver to take us to the airport.
At the time, we found her behavior unusual, particularly because she appeared to be laughing and mocking us as we returned the vehicle. We left wondering whether this was simply how customers were treated by the company.
Then, on October 1st, I contacted the company because I had not received my full refund. That was when I was informed that I had supposedly failed to park the vehicle in a particular location and that $300 had been charged to me as a result.

This is extremely troubling because no one informed us of this alleged violation when we returned the vehicle. The agent had the opportunity to inspect the car and tell us if there was a problem, but she did not do so. No email, text message, phone call, or other notification was sent to me on September 27th, 28th, 29th, or 30th regarding this alleged violation.
I only learned about the $300 charge because I personally contacted the company on October 1st to ask about my refund. After I contacted them, I was sent an email regarding the alleged violation. Had I not reached out, I have no idea when—or if—I would have been informed.

The timing and circumstances are deeply concerning. Given that the agent had already become disrespectful toward us after we declined to purchase additional products, followed by the lack of a vehicle inspection, her decision to immediately send us to the airport, and then the unexpected $300 charge that we were never notified about, the entire situation does not add up from our perspective.

I am not making assumptions about anyone's intentions, but I believe the circumstances warrant a thorough investigation. If there was genuinely a violation, it should have been documented and communicated to us at the time the vehicle was returned, especially since the agent was physically present and had the opportunity to inspect the vehicle.

This was our first experience renting from your company, and unfortunately, it has left us seriously questioning the way this situation was handled. We expect transparency, professionalism, and fair treatment as customers.
I am requesting that the company:
Provide documentation and evidence supporting the $300 charge.
Did she leave the car there for 3 days without inspection while she should have inspect the car almost immediately.
Explain why the alleged violation was not brought to our attention when the vehicle was returned.
Explain why no notification was sent to me between September 27th and October 1st.
Review the conduct of the agent involved, including the interaction surrounding the attempted sale of additional products and services.
Review whether the $300 charge is justified and, if not, issue a full refund.
I would appreciate a prompt and detailed response addressing these concerns. I hope the company will take this complaint seriously and investigate the circumstances fairly, because based on our experience, the handling of this matter has not been transparent or consistent with what a customer should reasonably expect from a professional car rental company.