No they cannot threaten you with with arrest. It is a violation of the law. Further, even if you did not pay the bill, the statue of limitations has likely run long ago on the claim. This means you would have a defense if they did sue you. Write to them, not just call them, and tell them you paid the bill, you dispute the debt, that they are not to contact you again, and if they do you continue to contact you, you intend to file suit under both the federal and state fair debt collection...