No response at UNISA

Does anyone actually work in the offices at UNISA? I have been trying the entire week to contact them telephonically on every phone number listed on the website, but I either get cut off, the phone rings unanswered, or the phone is constantly engaged. I tried sending emails but those just disappear into the ether. It is extremely frustrating!! what sort of institution are you running UNISA?? why is it so difficult to get to speak to a human person?