Since what they are doing is breaking copyright, in a perfect world you could get a lawyer to send a Cease & Desist letter, and then sue them if they don't take it down. But that obviously costs a lot of money...
Another option is to send DMCA requests to Google, to remove them from search results. But if they've taken many pages it will be time consuming. Anyway check here: https://support.google.com/legal/troubleshooter/1114905?hl=en-GB
A final option, if they are taking content direct from the feeds, is to add additional content to it, for example links back to your site. In qa-include/qa-feed.php line 406, change it to something like this:
$lines = '<description><a href="yoursite.com">This content is from yoursite.com</a>' . qa_xml($htmlcontent) . '</description>';