Overcharged for car rental

Never use their service unless you're willing to be ******. I rented a car from them on 1 May 2018 for a day. I collected the car at 11:30 am on 1 May 2018 then returned the car on the same day, 1 May 2018, at 21:50 pm . The following day I received an sms from my bank for an amount, a little above one days worth of the quoted rental fee, debited from my account with their name as a reference. When I got hold of them, I was told that the amount was for, going over the contracted millage and, returning the car late on 2 May 2018 at 21:50 pm. Their own check sheet clearly states that I returned the car on 1 May 2018 at 21:50 pm, I do not understand how anyone could've gotten that wrong. Now, I have to send emails, of the very same check sheet that they hold a copy of, to prove that I did not return the car late. This company is a joke!