Nobody at Vodacom can help me to activate visual voicemail

I was using visual voicemail on my iPhone with Vodacom without any issues until a couple of years ago when it suddenly disappeared and reverted to standard voicemail. Now, nobody at Vodacom can tell me how to enable visual voicemail again no matter how many times I phone through to the call centre and go through the hour long menu of options before realising that I need to speak to a consultant anyway. All I'm told is that it is already activated even though it clearly isn't. Luckily my contract with Vodacom comes to an end in the next few months.