Paid for a month when we left 4 days early they said they could not give me back my remaining 4 days at the monthly rate, it had to be at the daily rate. Which daily rate is of course more. Or they could just keep it.
Just September/October of last year we paid by month then as well, the RV had to go to the shop and I was given the remaining days of the month by monthly rate. It took three days to get credited the money back. But that's how long they said it takes.