If you know who they are and can prove it.
Out them publicly that would ruin their credibility for ever.
Neg SEO you can recover from.
Do the same for them.
Have you tracked rank drops in map pack that correlates to the appearance of the NAP spam?
Yes, so for example, I have a yelp citation, and they have created another yelp citation with my phone number but different title, or my address with and title but different number. When you say balance it out, are you saying just create more citations with correct NAP, and that should do the job?