Nationwide Credit. call me and threaten to ruin my credit Atlanta, Georgia

I had a business account with AMEX that I paid in full back in June 2011. Then the card was cancelled. Nationwide Credit calls me earlier this month and tells me that I still owe on this account,and if I did not pay them it would go on my credit report. At first they get my bank info and withdraw $200. Then I go to my bank and change my info and I get my $200 back. Then Nationwide calls again and I refuse to talk to them. Then Nationwide calls again,and someone else answers. The "debt" collector from Nationwide starts asking these people personal questions about me. This naturally , makes them uncomfortable. They ask "where is he". The point is they were told to stop calling me.

Today, I get a notice in the mail detailing my first $200 "payment" (which was refunded) , and it still says that I owe them $199. AMEX stopped sending me paper statements. I knew I had the debt though. I called AMEX last June(2011) and asked them how much I owed on my account. I paid the entire balance due, and cancelled the account.  On the envelope ,a Post office Box in Lehigh , PA ,is noted, and on the letterhead of the statement, an Atlanta , GA address is noted. Now, what belongs on the upper left of a business envelope?? The business name of course. What does it say on the Nationwide Credit envelope on the upper left??? PERSONAL AND CONFIDENTIAL. Correspondence can still be confidential, the proper place to note this is on the LOWER RIGHT of a business envelope. ''Personal and Confidential" is not the title of ANY  business.

Furthermore, people in the Telecommunications  business need to have an excellent command of the English language. One should not have to ask someone on the phone to repeat themselves. And ,do not call  me, and "leave me alone", mean something.. It doesnt mean making the individual and everyone around them uncomfortable,as that is exactly what you do best........I feel a deep sympathy for anyone who has had to deal with Nationwide Credit.