Is there a bus service from Changsha airport to South Bus Station at 23.50hrs?

In the airport, there are direct shuttle buses to South Bus Station, but the bus is out of service at 18:00. So you are suggested to take a taxi, and the fare is about CNY100 at night.
But I find the bus to Guilin depart from East Bus Station at 16:00. Why do you go to the South Bus Station.
Actually, it is more convenient to Guilin by bullet trains.