Editor not taking action after I reported plagiarism. What steps can I take?
Working with the editor, until that process is finished, is probably the only thing to do at first.  It will undoubtedly be a long process, with delays, so patience and persistence will be necessary. Try not to let the mobbing get to you, and try to remain calm and professional at all times, despite any pressure others may exert. 

If the editors, in the end, are unable to come to a resolution you accept, then the options will be (essentially) to escalate the situation or to let it go. But making an action of that kind while the editors are still working would be premature, in my opinion.