An appointment is not required for visa application, you can directly go to China embassy/consulate in South Africa to apply for China visa.

Nationals of South Africa are exempt from a visa to Hong Kong for up to 30 days, you only need a China visa to Shanghai. The required documents are:
a) One completed visa application form with one photo (passport photo) attached.
b) A passport valid for more than six months with blank visa pages.
c) For people who goes to China for the first time: 3 months bank-statements and original air-flight tickets.