Any further collections are invalid if a debt collector fails to validate the debt letter. These efforts would violate the Fair Debt Collection Practices Act, which governs how debt collectors may act and prohibits unfair, deceptive, and abusive practices. Violations of this act can result in severe repercussions and fines for the debt collector.
If they fail to respond, the debt collector must cease all activities against you, including but not limited to:
Calling you
Mailing you
Reporting the debt on your credit report
Filing a legal claim against you