Many consumers send very confusing GW letters, that often are interpreted as either DV or dispute letters, thus leading to defensive mearures on their part, including requests for more information.
Your letters initially go to a screening clerk, and not one versed in the subitities of the FCRA, or the GW process.
I can only suggest that you use, as part of your introductory paragraph in any such letters, a statment to the effect that this letter is NOT a request for debt validation, or a dispute of any accuracy of prior credit reporting.
