MTN's refusal to deal with *****

So more than 3 months ago I was alerted to the fact that an additional number had somehow magically been added to my contract and the person had been treating themselves to numerous data top ups at my expense. I did contact MTN's callcentre who's staff passed me like a bag of jelly beans in a prison from one depatment to another without any resolution of my problem. I later went into an MTN store where the manager told me that he would hard block the number while they investigate how this number got added to my contract. After multiple visits and still no resolution of the matter I was then instructed to go to the police station and get an affidavit stating that this number was **********ly added to my bill and that I was attemping to get it resolved, I took this affidavit along with a copy of my ID to the store and they logged the complaint. This was done in September 2020, yet as we head into December 2020 I still receive bills from MTN for THOUSANDS of rands for a contract that is worth R199.00 per month, wrecking my credit score and really causing undue stress. During my last visit I was told by an MTN employee I should make this public online as MTN is quick to deal with that as they don't want to look bad, boy was that a lie. Now I have received a final request for payment stating they want to cancel the contract for non payment, whilst admitting they have the ***** case open. MTN your service is ABYSMAL, I have been a customer for almost 15 years, well no more! oh and the service they have been charging me for has been cut off for three months, why cant I cancel for non performance of their contractual obligations?