Failure to honor promises credit note due to wrongfully billed - MTN empty promises

This is ongoing for months now where my account was billed incorrectly, MTN reverse the incorrect billing but not the vat. How they can remove the billing and not the vat is just silly. I have struggle now many times with this going in my 3 month with not getting this sorted every time I get feedback that the credit note will be pass but I just receive my new statement and it is still not done so MTN took my money from my bank and is not crediting my account. I just want to understand how do you allocate that vat as the billing was reverse. Alice van der Merwe previously promises a credit not and it did not happen. With the second she promises again that Veronica will pass the credit and according to my statement is not done yet MTN got money that was not owned to them I am getting sick and tired of MTN taking money that is not there to take due to there mistake