From my experience CA are very generous with their reward availability and their agents have a lot more flexibility to release reward seats than their Western counterparts.

Not sure if you have checked the Phoenix Miles website but it might give you an indication of availability.

http://ebooking.airchina.com.cn/AMRW...amrshop.action

Have you tried calling their Beijing office with the China pre fix? 00 86 4006-100-666

List of American Offices here;

http://www.airchina.com.cn/en/contact_us/america.shtml