1. In the sample letter, fill in your personal information. You have to tell your credit or debit card company about any error you're disputing within 60 days of when the first statement with the charge was sent to you.Get your free copy here! Use this sample letter to dispute mistakes on your credit report. See a sample credit dispute letter below. Our guide will teach you how to write a letter of explanation, plus offers a free template to help you write one of your own. A wellcrafted credit inquiry letter of explanation can explain honestly and clearly your financial history and your real estate ownership.