Dianne Russell owned $501 for an unpaid hospital debt. The hospital sicced Absolute Debt Collection Services on her. They sent a threatening letter. She paid the hospital directly. ADC continued to bug her, even after she told them about her payment to the hospital.
She, predictably, sued under the Fair Debt Collection Practices Act, as well as state law. ADC argued that the FDCPA didn't apply, as she never disputed the debt under § 1692g.
The problem is, § 1692g (debt validation) is an optional tool for debtors, not a prerequisite to protection against abusive debt collection practices.