Unfair Treatment

I was charged for 4 days instead of 3 days. I hired a VW Polo Vivo on the 15 April 2021 and i paid R5000 deposit upfront, the following morning the vehicle wouldn't start and i phoned their offices and after long wait they brought me another vehicle and took the 1st on away after fixing it, they said it had a problem with the tracker. I used the replacement vehicle till Sunday and returned it on Monday the 19 April 2021. On the 21 April i received my refund only to find that i was charged for 4 days instead of 3 days and when i called the office no one seems to care. On the 22nd of April I telephonically spoke to a guy called Carl who told me i was supposed to be charged for 3 days he will speak to Londi and sort it out for me.

All i need is my refund, no stories whatsoever. No one seems to care. i even phoned Londi today in the morning, she said she will phone back but she hasn't. We dont hire cars because we have a lot of money but we do because we need transport

Please help