Impossible to complete an application / register

We completed an application for Unisa for a PGCE last year - however we cannot finalise the application, get the fees account and be sure we are registered. We received an email requiring proof of undergraduate qualification in December and until Saturday were unable to upload these document via the website OR even get in contact with the call centre. Since last week, every contact number on the website has been out-of-service or permanently engaged and we have made over 100 attempts to call the number. My son has now started his intern teaching position however may well lose the position if he is unable to register and confirm his studies. I need urgent assistance finalising this issue.