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The first thing to determine is whether the debt collector now owns the debt, or is just an assigned collecton agent of the creditor.
If the debt collector has purchased the debt, then the OC would be out of the picture.
By reporting to the CRA, the debt collector triggered their requirment to send you a collection (dunning) notice within 5 days thereafter, wherein they must advise you of the current owner of the debt, its amount, and advise you of your right to request verification of the debt within 30 days.
That will inform you whether they own the debt. If the information you obtained from the CRA provides an address, you can send them a written DV without waiting for the requred dunning notice. In that DV, request the name of the OC and an itemization of the asserted debt.
The DV will invoke a cease further collection bar on them until they have provided the requested verification.
If you dont receive timely dunning notice, you can send a formal complaint to the FTC/CFPB.