Sentry Recovery and Collections, Inc. Debt Collection Complaint

Sentry Recovery and Collections, Inc. Debt collection department,

Medical Disclosure verification of debt Right to dispute notice not received Nevada

Someone called me up and told me I had a debt. They wanted me to go to their office and make payment arrangements. I asked for an invoice or a bill and they stated they would give me somthing in writing after I paid the bill. I told them the law requires that I receive something in writing regarding this debt within 5 days of intil contact. They sent me something in writing stating that I had 5 days to pay the debt in full. I do not believe this is right. Am I not allowed at least 30 days to refute and/or accept the debt once I receive written notification?