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You need, above all, to accompany your dispute with supporting documentation, and explain how that documentation supports your allegation of inaccuracy of their reporting.
It is not enough just to say "I dispute."
I would also leave out all the reference to their obligation to follow the statute, or threat of legal action. They are bound by the statute. No need for a lecture.
Just make sure it is clearly identified as a direct dispute over accuracy of their reporting under FCRA 623(a)(8), and provide the facts and documentation.
It does not hurt to send a dispute CMRRR, as their date of receipt begins the 30-day period for completion of their investigation.