Enterprise False Damages Wentzville , Missouri

My car caught fire and was totaled out. My insurance provided me with a rental through Enterprise.  The location I was renting from recently had a horrible hail storm. All but 2 of the cars were being repaired. I had to drive to work...4 hours away. So, I requested whatever they had in. They provided me with a huge F-1-50. It was the only thing in, so I took it. I had to get to work. The gentleman told me to roll down my windows, and enjoy the day! About 30 minutes later I try to turn on the air conditioner, its broke! It was in the 90s that day...it was unbearable driving four hours without any air. I called enterprise, and complained. They told me I could trade it out when I got to the city where my work is. I make it down, and go ahead and trade it in no problem. A few weeks later I get a letter saying I owed Enterprise $600 to replace the air conditioner. They claimed I ran over a rock ( on the highway) and broke the air conditioner unit. They had no record of my complaint. I also  talked to the damage recovery unit, and they said I was responsible since I accepted the car. Reading through Enterprise complaints, I see this is an ongoing problem. Would any of you want to get together & get some sort of lawsuit?