How to contact UNISA?

Can anyone help please? I am trying to get hold of UNISA. I have tried so many numbers already and they either just ring or I get the automated response that keeps you on the line with no further call answering. Emails is no help either. I need to know if my son's can study with them next year. The UNISA website is of no help to me and that is why I have emailed numerous times and try phoning several times a day. Any advice is appreciated