I work in SEO and regularly see large, poor quality link networks benefit sites, despite all Google's efforts. Other people have already suggested reporting the sites, but in practice you will never be able to keep up with someone who is really putting effort into this tactic.

It's best to avoid fighting this head on and stick to doing things properly - content, presentation and links. You may be under pressure now, but it's worth it in the long run. They will get their comeuppance.

If you're lucky you might even get an cryptic answer from the source during one of the Google Webmasters Hangouts - https://plus.google.com/collection/8926cB

(If you're interested I'm happy to have a five minute look in case I spot an opportunity you might have missed.)