Help with Marriage Certificate

[Lorand]

I have absolutely no information of my father's side of the family other than his name.  I would love to trace his parents and grandparents but cannot start until get their names.  The only info I have is the  date and place of my parent's marriage.

Janet Gilmour Balfour McCall to Jacobus, Johannes, Christofel Botes on 20 October 1945 in Johannesburg.

I would be very grateful if anyone can help with the marriage record.

Thanks
Lorraine