When I visited there last year, there was only one bus departing from Changsha West Bus Station to Fenghuang at 11:30, taking about 8~10 hours one the way. Actually, the better way is that you take a train from Changsha to Jishou firstly and then you could catch a bus at the square of Jishou Railway Station or from Jishou Bus Station to Fenghuang easily. The buses depart frequently from 07:00 to 19:30, and just takes about one hour to arrive in Fenghuang with a fare of about 15RMB.

Everyday, there are two buses from Fenghuang to Zhangjiajie, respectively at 0830 and 14:30. The journey is about 4 hours and takes about 40RMB. If you miss the bus, you could return to Jishou firstly and then take a bus from Jishou to Zhangjiajie. The buses here depart from 07:00 to 17:00 every 30 minutes.