Charged for company error!- I demand my full refund!

My insurance company rented a vehicle on my behalf. The day before the return date, I received a WhatsApp reminder stating that the car was due for return at 15:25. I adhered to this instruction and arrived at the branch at approximately 15:00, only to find that the branch was already closed. I immediately contacted the emergency number for that branch while standing on the premises. The consultant informed me that the branch had closed at 14:00 and advised that alternative arrangements could be made for me to return the vehicle the following day. My concern is: Why am I being billed for an additional day when I arrived before the stipulated return time provided to me?

I then called the emergcy number for that particular branch while at their premises, the lady then told me they closed at 14:00 and we can make arrangements to drop it of f the next day of which i did.

My questioned is now, how am i being billed for that day when i was there before the stipulated time? Tell me Nannette Hattings, why are you billing me for your company error?