I bought voice minutes on the 4th of February on the MTN app

I bought voice minutes on the 4th of February on the MTN app. I never received them, when I called they said they will ask their accounts department and I was not tge first person to call about a similar problem that day. I was promised a refund when I called a week later. I have provided proof that the money went out of my account but to this day I still have not received my refund.