They are almost certain to lie to you and violate your rights, and a written record will help you prove it later. What's more, debt collection agencies just don't have the capacity or competence to engage in written correspondence. Tell them to put it in writing and there's a good chance they'll just give up and move on, hunting softer targets.
One other thing debt collectors due is robo-sue their targets, bulk-filing boilerplate suits against debtors, real and imaginary.
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