Why does your website show available seats, but when I book you say the departure is full?
The process of getting train tickets is semi-automatic. It still needs a human being to go to the counter at the railway station, wait in line and buy your ticket. It can happen that in the short time this takes all available tickets are sold out. This can happen in only a few minutes. As we are not (yet) connected to the seat inventory system of Railways we show available seats until we get the information from Railways that a train is fully booked. Then we remove this departure on that day. It is a manual process, so the system can still show available seats when you got the message already that your departure is full. Our employees are humans. Sometimes they forget to update the availability. Then they are reminded and it works well for a while. :)