MTN Voicemail

When ever someone tries to call and I'm on the line at the time or out of signal, Instead of going to Voice mail, they get an automated response saying " The number you have called does not exist" Ive tried calling the MTN call centre numerous times. They say the voicemail has been reset and to turn my phone on and off. This has no effect on the issue!! Ive tried following the voice prompts to set it up myself with no luck.

I have no idea how this issue accused as I had a perfectly functioning voice mail the one day then the next day this issue occurred.

If you phone the call centre back you never get the same person to follow up on the issue. Just the same standard procedure is followed with a reset, WHICH DOES NOT HELP..

If they call my number they will see what Im dealing with, but we never get this far. Any help in rectifying the issue would be greatly appreciated.

My numbers ********** 219.