MTN is ******* , I regret opening an account with them

So I opened an account with MTN in 2018 which I was paying fine , I’ve been trying to call MTN’s customer service to close my account they transferred me to the legal department, legal department sent me bank details and I paid . I received a paid up letter but it’s been months of back and forth of them not removing the debt from ITC, their legal department confirmed that it will take about 60-90 days but it’s been more than that. I spent so much time and money on the line with their customer but I’m not getting anywhere.