Debt collection — Ditech Financial LLC (IN)

Debt was already discharged in bankruptcy and is no longer owed. XX/XX/XXXX Di tech financial is trying to collect old bad debt on a home that I lost 17 years ago to foreclosure. XX/XX/XXXX I wrote them back certified return receipt that the debt was no longer valid. XX/XX/XXXXToday I receive a letter with no description of what they are trying to collect on. Included was a ditech account number and only that they were trying to collect a debt? I want these people to stop and to close my account number.