I have booked many flights with them and am very familiar with their policy. To change or cancel your confirmed booking, you need send an email to TravelChinaGuide (TCG) at travelchinaguide.com|flight, or fax to them through 86-29-8526 1922. They will calculate your refund on the day when they receive the written cancellation by Beijing Time.

change or cancellation policy
Before they issue the tickets, clients may enjoy free change options. If you have made the payment to TCG, any cancellation required by you after issuing the tickets, the service charge of USD6.00 net per ticket will be levied accordingly. After the flight tickets are issued, any change required by guests on confirmed flight date, time or airline companies must be notified TCG by written, mail or fax. The change terms are subject to the airlines’ Change & Cancellation policy. TCG will calculate the change and cancellation fee from the day they receive the cancellation notice by Beijing Time. And the service charge of USD6.00 net is nonrefundable for any cancellation or No Show.