There's only so much you can do and you should ask yourself if it's worth the trouble, personally I just resigned to the fact that some stuff I can't get removed. If the site does not respond to DMCA notices you could try contacting their webhoster but that's hit and miss too. What's the site URL?
You always have the option of trying to take them to court but I doubt that it's worth the expense and depending on where they are located there might be nothing you can do about it. Sucks but that's the way it is, not all countries respect copyright laws.