It could be that at the time you bought your tickets, some seats were reserved, but were later made available for sale. That's why they were displayed as unavailable at the time of your purchase. Unfortunately, we are unable to anticipate situations like this, and we have no control over them. Kindly keep in mind that once tickets have been purchased, we're unable to accept any requests for ticket exchange for better seats. For this reason, make sure that you are happy with your seats before submitting your order.