Paid up letter

Old mutual sold my account to MBD which I paid in full however now I have to get the clearance certificate from debt counselor but I can't because MBD doesn't want with a paid up letter I call *** number numerous times and hold for hours but still nothing. Can the please give me my paid up letter and stop playing hide a see with people, when they do collecting call you none stop but when it's time to get what's due to you they playing games. You *** Mandla,