MTNs Gross Negligence, terrible service and refusal to refund large amount debited from my account

I have been a customer of MTN for 15 years. Never have I ever been more disgusted in the service and gross negligence of the business and it’s complaints resolutions staff. In August 2021 I was debited R2869.04 for a service they could not even explain it was for. They then acknowledged the error and advised I would be credited the amount of which I declines as I needed the money put back into my banking account. To this day I have not received those funds into my account. In March 2022, MTN again incorrectly my account. An agent name Ayanda and Sizwe called and emailed me two months ago to confirm the amounts will be reversed to my account and still this has not occurred.