In my opinion, a DV now would accomplish nothing.
First, it would most likely not be timely, and thus not invoke any cease collection bar on them. Second, even if timely, the debt is paid, so their collection must be reported as $0 balance under collection, and closed. They are no longer collecting, and thus could care less about a cease collection bar.
Even if they did choose to respond, which I see no reason for them to do, they could simply respond "We verify that the debt is $0."
It might have been better to have offered payment through the debt collector in the form of a PFD rather than directly to the OC, but that is water under the bridge. The debt collector has no obligation to delete based on payment of the debt.
Your path now would appear to be a GW letter.
