WebAfrica threatening to report me to credit bureau for not paying a non-existent account

When I moved into my new apartment, the previous tenant asked me to sign a form to change ownership of the WebAfrica account to mine which I did. However, on the day I moved in, there were no fibre services active on the WebAfrica account when I logged in, and a customer service representative confirmed this when I queried with them. I thus signed up with Cool Ideas and had the line moved over to them.

Thus began threatening emails and text messages from WebAfrica that I had cancelled a fibre service (which was not present when I moved in), and that I needed to pay a penalty fee for early cancellation of the contract. The apartment had a WebAfrica router from the previous tenant which I returned to WebAfrica (and they confirmed receipt). A few people contacted me occasionally from WebAfrica and I explained the situation and they promised to get back to me. This never happened.

A week or so ago I received a text message from WebAfrica saying I was in default for a debt and they were going to report me to damage my credit score. I queried with a customer service representative who said this was a false message and I could ignore it, and that they would lead "Head Office" know. But it didn't seem right, and after querying a few more times another rep produced a statement which I had never seen nor been sent, amounting to about R3'000!. One of the fees was a "clawback" fee!

It is impossible to get through to someone on the telephone to understand what is going on, and I'm worried that WebAfrica is going to report me for a problem on their own billing system.

I request a full cancellation of any supposed 'fees' and a commitment that I won't be 'reported' for not paying a non-existent account that was never mine.