China post / EMS max weight

Hi , the information given above ,says China post and EMS will accept up to 30 kgs and 30/40 kgs respectively, for surface mail, however I have tried both options for a large package weighing 24.5 kgs, and both have refused, saying 20 kgs is the maximum . I reside in Sanya, and need to find a way to get these items shipped to NZ ,surface mail. Any help appreciated.