Account sent to collection from 3 years ago

We terminated service and returned the equipment when he left college.  

No contract to my knowledge.

---

@philsphan wrote:

Just found out that my son's college comcast account from 3 years ago showed a balance due.  Found out when we looked at his credit score.  Called Comcast who indicated the balance was due to unreturned equipment.  This was incorrect as my husband returned.  Service rep indicated that they would take care of it.  We now just received a notice from a collection agency and called again.  Now Comcast indicates that he owed for service.  I remember calling and going over his last bill and confirming that nothing else was due when I paid it.  I have no records from back then.  How do I resolve and get the ding on his credit removed.  

---

Was there a contract involved with his account?  If so, was the account terminated during that contract? 

@philsphan