Unresolved MTN penalty charges

I'm loyal MTN customer of 23 years. Last year (2020) I decided to take an additional contract for my business. It then turned out that the contract had not been done correctly as per the MTN processes, as a result of which the line could not be activated. After a long (4 month) fight with MTN, the contract finally got cancelled on 09/02/2021, with a promise that I would not be charged a penalty fee for early cancellation

On the 27/09/2021, I received a statement and an invoice from MTN clearly showing that I was charged for this cancelled line. I've been querying this with MTN since March 2021 and there's still no resolution. I was charged R399 plus an additional R57 for a line that has been cancelled. The charge formed part of an R855 that I was billed in the 27/02/2021 invoice. I’ve been asking MTN to please credit this amount to my current contract. Instead they chose to send me a document with transaction details of the account which does not resolve my issue. I’ve sent them a copy of the 27/02/2021 invoice, where it shows clearly on the invoice that the R399 plus the R57 were been billed in lieu of the cancelled line. I'm still waiting for my credit. I am very frustrated with this organisation and their *********** staff. The line in question was never activated, never used and was subsequently cancelled.

I need someone competent and senior at MTN to call me to resolve this issue as a matter of urgency.