Blacklisted for no reason

I was with mtn for a couple of years. Had data and cellular contracts with them. At the end of the contracts I terminated the packages and we parted ways as friends. That was 2023. This year I was going to get a line of credit and I am told that I am blacklisted by mtn. I called in but can not get a human to help. The only number I know is the data contract number but I think it has be reassigned cause I am being told about airtime. I need to get this resolved and I do not know how.