Business ProfileforEnterprise Rent-A-Car

I rented a car from Enterprise rent-a-car at the homestead/munhall location around noon on Aug. 3 to attend a business training session for the week after. After I drove the car out of their branch, I quickly noticed that one of the tires is nearly flat (photo proof attached); later I also found out that one of the back doors is also not properly installed and shaky. Since their branch is closed after noon on Saturday and I need to leave on Sunday for my business trip, I tried to bump air in the flat tire and found it was broken and cannot take in air. As the car is not in a drivable condition for long trips, and I cannot get a replacement on time since the branch was closed, I have to find an alternative family car to drive for my trip and left the car at home. Due to the weekend and my busy schedule on Monday, I called the branch on Tuesday morning to pick up the car, but they refused to refund the rental fee to me, saying the car was in my possession for a few days (they only picked up the car on Thursday after we call them multiple times) and I need to pay for the time the car was with me. However, the car was dysfunctional at the very beginning (as proven by the photo) and it only incurred 100 miles during my possession, which proved that I didn't use the car. The branch employee also mentioned that they are extremely understaffed, which likely explains why they are renting people cars that are not properly maintained and dysfunctional. This experience has severely impacted my business trip (the car was in fact rented under the corporate agreement between my employee and enterprise). Because of the disruption is caused by the dysfunctioning of the car in the first place, and I have tried my best to return the car as soon as possible within my business schedule, I believe they should provide a full refund to me. I advise anyone who's considering renting a car to avoid Enterprise since their cars are extremely poorly maintained.