I suggest you not assume anything about availability and shipping, and rather just get in contact with the #1 worldwide producer if meat cultures and biotics, Chr. HANSEN. They ship all over, with packages that easily tolerate normal shipping and heat. For example where I live in Phoenix, Arizona. I recently contacted them and rapidly got return emails from both a tech specialist as well as my area sales person.
They are a global company, and their web page lists South Africa as one of their regions, with an email contact for SA of general_enquiriesZA@chr-hansen.com.
Here is their webpage, where you can further research contacting them:
Here is their contact page for their South Africa office: