PLEASE ASSIST ME - MTN ACC handed over to CSS

Can anyone please assist me .. since 2019 I've been struggling to sort out my account, it is paid in full but no allocations has been made, i can't get a personal or home loan due to this. I've been begging for assistance and don't know who to contact anymore. I'm doing everything in my power but MTN never assists or call me or anything, and why do they refuse to give me documentation on my own account??