This sounds like a scam. Be wary. If further help is needed, Use the Avvo search tool to find an attorney. https://www.avvo.com/find-a-lawyer

Do discovery, prove your claims and make the creditor prove their claims.

Yes. Consult with experienced attorneys. Use the Avvo search tool to find an attorney. https://www.avvo.com/find-a-lawyer

Contact the police and the toll collector agency.

Let the debt collection know you were a victim of fraud, in writing.

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As we cannot know, contact the utility to make sure and attempt a work-out.

Even if disputed, the purchaser of a debt can sue. But you can defend and have a good chance of winning. Consult with experienced attorneys. Use...

If you cannot get resolution through a government agency, Consult with experienced attorneys.

It is proper. An attorney does not need to discuss this with the client.

Consider Bar Association fee dispute Arbitration or filing a lawsuit.