The CFPB provides formatted letter templates to help you write ... within 30 days of receiving the initial collection notice if you dispute the debt or have doubts about its validity.

Finding an unfamiliar collection ... directly dispute debts with a debt collector by requesting debt validation within 30 days of first contact. To do this, you'll write a detailed letter ...

Could your debt ... a 609 dispute letter to a credit reporting agency is the cost of the stamp, ink, paper and time spent writing. That is, unless you choose to pay a nominal fee for a template ...