Insulted me

I called the national call center to change the time of my pickup to 5pm, after the local Hertz branch told me when I called Monday (2/29/2016 @ 3:14pm Central Time) that she can not guarantee my car an hour earlier (original pickup was scheduled for 6pm). I called the national call center (***) at 3:22pm and asked the agent to please change the time. He quickly did that and when I asked him to please explain why I am charged for 3 days if I'm renting from Monday 5pm (Lubbock) and dropping off Wednesday 5pm (Las Vegas). I count two days. He kept telling me I pay for Monday, Tuesday and Wednesday (3 days) and IMO it was two days (Mon-Tues = 1 day; Tues-Wed = 2 days) He then insulted me by saying this is \Elementary math\"!!! Really! I am in customer service, deal with customers on the phone daily and I will not say this to anyone!!! I then asked for a manager (Robbie) who explained to me that the time change is causing the 3rd day charge. Thank you to Robbie for looking into it a little more to keep a customer happy. Very unhappy with the agent's attitude. I am very sorry I did not take his name. Maybe my time stamp can help find him. "