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If it is clearly not your debt and you are willing to place that statement in a sworn police report, then the debt collector will be totally removed from any involvement in removal of the collection from your credit report.
You can file a police report, and then send a copy of the police report to the CRA, along with proof of identity, and the CRA must then block the collection from your credit report without any verification or involvement of the debt collector.
See FCRA 605B and the "Victim of Identity Theft" sticky-post in the upper section of the General Credit Topics forum.
If it was a joint account, then a divorce decree assessing who is obligated for future payments does not remove you from your obligation with the creditor.
The creditor will, and legally can, still pursue the debt with both parties.
You can then pursue separate civil litigation against the former spouse for their violation of the terms of your divorce decree, but the creditor is not involved in that process, and it does not change the terms of your contract with the creditor.
If your only basis is that a divorce decree addressed continued liability for repayment, that is not basis for asserting the debt is no longer yours.