You should probably include the citation of 15 USC 1692g. You can look into Jersee's VOD success pdf file for more accurate one.
Wait, scratch that, the 1681 parts are what you want, not 1692. 1692 is for debt collectors, but 1681 is for credit reporting agencies. Take a look here for more info:
http://www4.law.cornell.edu/uscode/15/ch41.html
You might tell them that you've tried to get verification from the alleged creditors (if you have) and are now turning to them, since they are reporting unverified alleged debts.
Also, mention that if they can't verify them that they must be removed from your credit report. Tell them this isn't a dispute over an amount, but a request for verification.
Any other comments? Jersee?