Had an account with ...

Had an account with them that is a paid up account when I say paid up means all installments paid up, but I'm experiencing some difficulty to gain fanancial help to other companies due to them saying I'm in arrears when I tried to explain to them they insist that I must produce a paid up letter from the debt collectors I tried to explain that there was never a debt collector to no avail I'm still regarded as I'm in arrears with them so they blocked me access to other companies