DON'T CARE ATTITUDE BY MTN FOR REFUND DUE TO CUSTOMER

I upgraded my contract with MTN on 05/11/2021. Account no.: BA***. My billing period runs up to the 27th of each month. For period 05/11/2021 to 27/11/2021 they billed me on old contract and the new contract. I have been fighting with their customer services department from beginning of December 2021 for my credit on the overcharge. They keep insisting that there is no credit due but fail to provide proper reasoning. I repeatedly requested that the matter be referred to one of their senior accountants but they failed to do that. I referred the matter to their complaints department on 24/12/2021 and lodged a complaint on hellopeter. To date there has been no response from their complaints department or the hellopeter review. If they have nothing to hide and can justify why there is no credit due to me then why don't they provide responses to the complaints to show that they are in the right? A big company like MTN is lacking customer service and is handling matters in an ********* way. I am waiting for 14 days to elapse from date I referred the complaint to their complaints department and will then lodge a complaint with ICASA. Fortunately there are controlling bodies to handle companies that give customers poor customer service. MTN management should be ashamed of themselves.