The FTC has a site with a lot of helpful information on helping you resolve identity theft, and even will help generate the correct documentation and direct you through the maze. https://www.identitytheft.gov Note the it is literally the business of credit agencies to blithely ruin lives so they will be very unhelpful if they can.
Huge differences in quality between your first and second paragraphs. It is the business of credit agencies to serve as proxies of your credit worthiness. They prosper when more people are in the credit pool and are able to take out loans.
Or maybe there's more to it than that?