See here the link to the DAFF Website for the updated list of the DAFF Accredited Laboratories:
https://www.daff.gov.za/daffweb3/Branches/Agricultural-Production-Health-Food-Safety/Animal-Health/Epidemiology
See here the link to the SANAS website for the SANAS Accredited Laboratories:
Ermelo, Vryburg, Stellenbosch, Allerton, Potch and OVI laboratories can all test for Brucellosis