There are many different ways that you can attain your National Senior Certificate (NSC) outside of high school.
But, unfortunately, Unisa is not one of them.
Unisa only offers higher education courses that already require you to have your NSC.
There are however many other routes that can be taken to get your NSC outside of high school, like distance learning institutions
With no classes, distance learning is perfect for those who can't take time off work to study. The downside of this is that you need to be disciplined enough to study in your own time.
A Matric certificate isn't the only option available to you.
Another option on TVET colleges.
Many TVET Colleges offer National Certificate (Vocational), also known as NC(V). This will see you obtain a NQF 4 qualification which is the equivalent of Matric.
NC(V) puts emphasis on practical skills such as Business, Management or Hospitality among others.