DV letters are sent only to debt collectors, not to creditors, so I have no idea how they apply to issues with the creditors.
Additionally, DV letters arent demands, they are a process whereby you can, if timely sent, require cessation of collection activities by a debt collector until they choose to provide validation of the debt. And unless sent within 30 days of their dunning notice, they do not even invoke a cease collection bar.
DVs must come from the consumer, not a credit repair organization.
Sounds like a high-fallutin' smoke intended to make you feel they have more to offer, and has little if any relationship to any issues of credit reporting or CR deletion.