National Car Rental review: unethical behaviour

I rented a car from National Car Rental in Englewood CA on 7/19/19. I had reserved a mustang convertible rental agreement [protected] and upon arriving at the pickup point no vehicles were available. After standing around for 20 minutes of a black Mustang convertible was borrowed from Alamo to satisfy our reservation. Upon receiving the car, I had pointed out damage to the left rear bumper and quarter panel. The attendant who upon thinking back was driving a little hastily while pulling the car up said it was fine and I assumed it was ok and figured that is why Alamo had it sitting around. I didn't think to do anymore with it since we had been waiting so long and I was tired from traveling. The next morning, I woke up and feeling uneasy about the whole situation I took pictures of the damage. Upon returning the car the next day at 9:40 AM on 7/21/19 I was accused of causing that damage. I told the attendant who we dropped the car of with and she was very rude about the whole situation. I asked to speak to her manager and another lady came over who was even more rude to me and my wife. I expressed my displeasure and she told me to go talk to the station manager inside. Upon talking with Brittany Dickerson she went and looked at the video footage of the car leaving your facility and said that because it was a black car and 9pm at night that she could neither confirm nor deny there was any damage to the car. She assured me she was going to check the cameras earlier in the daylight and see if she could see any damage. She said she would call us at 5pm when our plane landed. She was very polite while we were there but now I feel like that was just a front to get us to leave so she didn't have to deal with us anymore. To my surprise she never called. I attempted to email her on 7/22/19 and she did not respond. So later that day my wife called the number Brittany gave us and we were directed to a generic customer service representative who looked up the rental agreement and assured us there were no damage claims on our account so the issue must have been resolved. Now today on 8/6/19 almost 3 weeks later I get a call from your damage claim department trying to accuse me of damaging the car. I did not damage the car and waiting almost 3 weeks to contact me is just making it more difficult for me to resolve this situation. I am not sure if your employee's damaged the car while retrieving it, upon think back she was driving a little fast and was very hasty to get us on the road. Maybe it was damaged previous to this on Alamo's lot that is why they were more than happy to give it up but either way I am furious about this and how this situation was handled. My wife and I were frustrated but polite with your employee's. I am a long time customer and my company Polaris Ind. rents from you all the time and have had nothing but great experiences from many of your other facilities. I feel like I am being taken advantage and being treated very unfairly. I am hoping you don't wait another 3 weeks to respond to this complaint as my thoughts on your company