Unfair listing after 13 years

I recently notice that African bank has put a d360 red flag on my transunion itc and experian which does not allow me to apply for a loan. I have contacted numerous times where they advised me that I dont have any outstanding debt to them but still they cannot assist me. As per their system I had a personal loan in 2005 which I dont agree to . This is the account where they listed me on a red flag. But after that in 2014 they approved a loan of mine that was paid, however now I am still listed on ITC. I have a paid up letter from african bank but I dont understand why they dont clear my name and leave me to look as if i have bad debt