What a struggle to get a paid up letter

Let me say I am quite disappointed that i need to be calling cell c over and over again to get a paid up letter and instead they send me the statement. Come on guys my account has been closed and paid up for more than 5 years however I am still listed as a defaulter for only R 450 for more than 5 years. You guys are really killing my credit score shame. I am tired of calling and be kept on hold but again its me who is listed……