The other thing I forgot to mention is that Dun and Bradstreet has a collection agency,  if your client refuses to pay or doesn't return the calls, etc..  Dun and Bradstreet puts it on your clients company credit.
This is bad for companies that work directly for banks as banks always check your company credit BEFORE taking you on as a vendor. I did this with Courthouse Connections in Atlanta, Ga back in 2004.
Even though D & B wasn't able to collect I felt there was some justice done.