Dishonest DO JOT RENT FROM THEM

I rented a car and was told they will only put the amount for insurance nzd300 through my cr card once we return the car ...SHOULD WE RETURN IT BEFORE THE TIME WE BOOKED IT FOR THEY WILL AMEND THE AMOUNT FOR THE DAYS WE HAD IT...we booked for 6 days but returned the car after 3 and a half days😡😡😡 this is dishonest...i sent them emails which they do not reply on