Is it a scam

[Judeez01]

I received a collection letter from ACI AMERICAN CORADIUS INTERNATIONAL, LLC

The letter says that I owe $100.00 on Acct. #<removed>. I believe 

this is a scam. 

[rpatience]

I also received a letter from them. I sent a response letter to dispute. They sent me a letter back with the claim. It had my name but not my account email address or a transaction that I have ever participated in. I don't know if fraud or a scam at this point.