Visual voicemail

Voicemail is a carrier feature and they are responsible for your email. The only difference with visual voicemail on the iPhone is that the carrier has to support it. If they do not, then all you get is regular voicemail. They need to configure your voice mailbox for you.

I would have to agree with that. If you can call back, see if you can move the call from customer service to a 1st or 2nd tier of technical support. Someone has to know what is going on if they are providing voicemail. That is one of the issues that can occur when you are dealing with an MVNO. Good luck.