My question involves collection proceedings in the State of: South Carolina

I recently received a verification bill from a colletion agency for Verizon. I was never late on my bills and perplexed why I would still owe money. What I received was a bill that shows payments in full. The only charge left was a cancellation fee. I was taken over by Verizon from the Alltel merge. I never signed a Verizon Contract. Can I still be charged a Cancellation fee? Can I request the collector to show proof of a signed contract?