Dear Sophie Billington,
Thanks for contacting Top China Travel!
I am sorry to tell you that we do not offer bus ticket booking service seperately. You may have to go to the bus station in person to book the tickets. It is suggested to book 2 or 3 days in advance, especially in tourist peak season. Otherwise the tickets will be sold out and your travel schedule may be upset.
If the bus tickets are sold out in Chidianzi station, you can also go to Xinnanmen Bus Station to book bus tickets to reach Jiuzhaigou as well. The condition of buses in Xinnanmen Bus Station is better than those in Chidianzi station. It takes about 10 hours from Chengdu to Jiuzhaigou by bus.
Any further request or question, please feel free to contact with us.