Afni, Inc. False claim, Got address that is never used, offered a settlement of cheaper than orginially "owed" Bloomington, Illinois

My husband received a letter in the mail from Afni, Inc stating he owes quite a bit of money.  It states the orginial creditor was AT&T mobility.  He has never used AT&T for anything.

The weird thing is, it was sent to our house, which he doesn't use that address, ever.  Even on his driver's license his address is his mother's.  We have never received mail in his name to our home. 

I went to the website right away and enter the account number and it stated the website was down.  I, also, called the number but they were closed.  I googled the company then and found that other people have been scammed or mislead by the company.  I am now following steps to get this resolved with them.  I am contacting my local and state governments and going to write Afni letters stating I need more information on this claim and whatnot. 

I hope to have this resolved sooner than later and without too much of a headache.