About 2 years ago I had a similar issue with a large Chinese website which had taken around 400 pages of content from my site. I threatened them with a DMCA which got a response from them, but they weren't being very quick about getting rid of the content. What really worked was when I actually telephoned their European office and spoke to someone there. She was as horrified at their theft as me! Turned out it was a rogue 'writer' who didn't like to write his own material.
Is there any way you can contact them directly? DMCA threats when you have solid proof you are the original source usually stop most sites from stealing content very quickly. Sadly they'll just move on an steal from someone else. I've found DMCA threats sent directly to the site owner to be very effective many times.
If you do send one to them don't rant at them - however hard it is to restrain yourself! It's much better to come off deadly serious and proffessional - prove to them you've got solid evidence, and explain that it could result in their entire site being punished.