If you have applied at UNISA you might be able to do a late registration (will have to pay a fee I assume). If you haven't applied, don't bother - you are going to have to wait till next semester.
I tried - in vain - last year to make contact with any one in their economic and management department. Emails, telephone calls, etc were all a complete waste. I have no choice but to study part time and need to complete my B.Com. I am obliged to make a pilgrimage to one of their centres for assistance. Like Ninja'd Said, I think this application might be too late. Nothing stopping you from make preparations for the next semester.