I need to contact them but I don't have enough airtime

I need to contact them but I don't have enough airtime. I managed to call in and spoke to a Nomfundo. I told her that I was about to run out of airtime and asked her to call me back. I gave her my number. She said she would call me back, but that was yesterday morning. She never called me back. And this morning I have been trying to get hold of a live via their WhatsApp chat and it's been utterly useless.