No one answers the phone to join the scheme

I've been trying to call Bonitas hotline on *** for several days as I'm looking at joining their medical aid but the phone rings endlessly with no answer! I've tried their so-called WhatsApp number on *** but the number doesn't register as a WhatsApp number. I've called the other departments eg: pre-auths to try see if I can be referred elsewhere to a consultant and still nothing. It's like you really don't want new customers. Why is your call centre a huge mess??