First, the debt validation process is not the proper procedure for dealing with a debt that you assert was never authoriized by you.
That is done by way of the identity theft process under FCRA 605B. That process does not require any proofs on your part. It requires only that you put your assertion that you never had the asserted account and that the debt was never authorized by you into the form of a sworn police report.
If you submit that police report along with an affidavit, the CRA is required to block the reported collection from your credit report.
A debt collector is not required to respond to a DV request, and any issue of lack of validation on their part is not relevant to removal of the collection from your credit report.
If the DV request was timely, its effect is to require the debt collector to cease futher collection activities, not to validate/verify the debt.
In the posted scenario, however, the debt collector did provide what they consider to be adequate validation, so they consider themselves to no longer even be under a cease collection bar.
Neither the DV process nor the dispute process under the FCRA compels the debt collector to "prove" the debt. They must investigate and make a determination as to whether that investigation supports a finding of validity of the debt.
The alternatives at this point are to either sue the debt collector, if and when they resume efforts to collect on the debt, for violation of a cease collection bar, or to follow the identity theft process set forth under FCRA 605B and provide a sworn police report supporting the assertion of account not mine.
