I Paid Up my account but still shows as unpaid

I have been owing credit U, since 2008, they were phoning me demanding me to pay now i have paid the account in Full last month. I phone them every week asking for my confirmation letter that to confirm that the account is settled then they tell me that they are busy the account is not yet closed and is still reflecting on ITC as owing.<br> <br> Can anyone help me to resolve this issue because its affecting me negatively on credit bereau