1. This is the full tracking of your parcel:

China Post Register Air Mail Tracking System
Parcel No.RK498464409CN tracking result
2016-08-01 16:07:11.0 张家港city 广告分公司 received
2016-08-01 17:31:59.0 张家港city 广告分公司 customs scan
2016-08-01 17:43:52.0 leaving 张家港city 广告分公司 ，next station 张家港
2016-08-04 08:11:22.0 Suzhou Transit Station export security scan
2016-08-04 10:28:22.0 Suzhou Transit Station export customs scan (domestic transit )
2016-08-22 14:01:14.0 arrive Suzhou city Post Office parcel process center delivery office
2016-08-22 14:04:07.0 Suzhou city parcel process center received
2016-08-22 14:04:07.0 Suzhou city Post Office parcel process center 已rejected
2016-08-22 14:04:34.0 Suzhou city parcel process center customs scan
2016-08-22 16:34:11.0 leaving Suzhou city parcel process center ，next station Suzhou center

2. As you can see your parcel was rejected here:
2016-08-22 14:04:07.0 Suzhou city Post Office parcel process center 已rejected

3. You should contact seller as soon as possible and provide him with the above full tracking. Tell him the parcel was rejected possibly on the Export Customs scan.

Hope this help.