During the summer high season and a few other times throughout the year, tickets booked at the last minute can become sold out before we can complete your order. It happens in less than 1% of cases. We will email you a list of possible options for Vietnam Railways, and as soon as you reply, we will book your alternative. If there is no alternative, we will refund you in full. For the private railways, we will automatically switch you to a provider of equal price and comfort level should your desired train become unavailable. There is nothing you need to do in this case; we will book the available train for you and send you an email notifying you of the change. We promise there will be no noticeable difference in the quality of service for the new booking.