Repairing your credit takes time, be patient. I had a person in my workshop recently tell me that she mail off letters on the same items every 15 days thinking it would bring her quicker results. The result? The credit bureaus deemed her dispute as frivolous and refused to investigate.
Wait the 40-45 days for a response before taking any action. If they respond quickly, great! If not, your next letter should address that appropriately.
Hope this helps!