Settlement letter

I am so disappointed at the service I got from MBD collection,I settled an Edcorn account with them 6months ago and settlement letter was promised 7days later.I have called,emailed,begged to get a letter and I have not yet received the letter.instead if you lucky enough to speak to an agent after a 5min hold on the phone,you would be cut off while the consultant tells you their waiting for system to retrieve your information....you will call back to same routine or no response but cutoff.I need that letter as account still shows active and another company of collectors is calling me non stop for same account