You may have the following methods to solve this issue, afforded by the law:

1) you may negotiate with the seller directly;

2) if this is a consumer goods matter, you may seek mediation from the local Consumer Protection Association. If you are in Shanghai, you can log onhttp://www.315.sh.cn/xx315wsts.htm to register your claim;

3) you may seek remedy from the relevant administration of industry and commerce. You can call hotline 12315 to register your claim;

4) you may seek arbitration according to the agreement with the seller. (If there is any, otherwise, relevant PRC contract law clauses may be applicable).

5) you may file a lawsuit in the court in which case you need to ensure you file the lawsuit within the statute of limitations.