Zero response from MTN to 5 months ongoing technical fault

I am an MTN Contract Customer. Since late 2019 my voicemail service does not work. In menus on the phone I have recorded a personal voicemail response and this has always worked fine for many years. On my end I have changed nothing and the recorded message still shows as active from my iphone.

But suddenly since late 2019, callers only get a "Voicemail Lite" response which does not even work, as it does not ever inform me that someone called. I have reported this to the call centre 3 times. The latest was on 12th March & I was given a technical ticket number but since then absolutely nothing has been done to fix it.

Also: Call centre staff were never any help as they only deal with account issues. Recently it has got worse. It has become impossible even to get hold of a human being on 135. The IVR does not even work!

I have also emailed the same query to *** and only ever got an automated Enquiry Reference Number and nothing else to follow that. I have also tried posting the problem on their Facebook page but also got no response.