In some states the fee agreement would be voidable by the client in these circumstances.

What you describe seems like fraud for which you would have a valid lawsuit.

If there was something in the prior contract allowing continued billing in the particular facts they may be able to pursue the debt. If not, you...

They might have trouble suing you or reporting the debt but if they take the effort the misspelling will not be a valid defense.

Yes you should file an answer or other motion. Consult with experienced debt collection defense attorneys in the state where this occurred to see...

You can proceed with execution on the semi.

Social security money is exempt on filing for the exemption.

It might be a scam. Give them no information. Have them confirm the debt. See if it appears on your credit reports.

If the other person is on the account the police will not likely get involved. You will need to sue the co-signer.

The statutes of limitations are laws that cannot be changed by persons or companies.