What should I do when a predatory conference will not listen to us and the journal might retract our paper? I was in my first semester that a professor asked me for a collaboration with someone else. We have started the project but because of Mr. C bad behavior and lack of contribution our professor fired him from the project. 
Consequently, we had published a paper 2 years ago based on that project. After a few months, we have accidentally found out that the initial draft of the paper in another language has been published at a conference with Mr.C name and his wife on the conference proceeding. It is worth mentioning that we kept our data and updates of drafts in a shared Dropbox account that Mr. C had access to. We emailed to the conference and told them to remove the conference proceeding because it had been uploaded without our permission, so they removed it from the conference proceedings. Few days after that the journal that has published our paper sent us an email saying that someone (that we know its Mr. C) told them that our paper has published before and it is a case of a redundant publication and plagiarism. 
Then we have told everything to the journal about the situation. 
Unfortunately, because Mr. C have powerful connections in government he was able to make the conference proceeding available once again! now the conference won't listens to us and they don't answer us. 
The conference proceeding is in another language but the context is about 80% the same as the journal paper that is in English!
We don't know what to do. 
We did not hear about this case from the journal for 3 months now. 

Is it possible for the journal to retract our paper at this point because of the duplication and redundancy or plagiarism? What should we do?

UPDATE: The conference website is down known and not available anywhere at the moment but the conference has sent the proceedings to an indexing website which is only available in our native language. Also in that website proceedings can be bought only with the X currency and it is not an international indexing website. 

Still, I am scared that there might be a possibility for the journal to retract our paper due to duplication! Is it possible?
The key statement in the above may be "Mr. C have powerful connections in government". That is an issue that may be impossible to overcome. If there is an ethics process in your profession generally, you can bring things to their attention. You can bring it to the attention of the conference committees and journal editors. Unfortunately you may be fighting powers that you can't overcome. 

Given sufficient power and influence, yes, they can do whatever they want - ethical or not. If you can shine enough light on it you might get some satisfaction and it may come back to haunt Mr. C in the future, but making powerful enemies in some places isn't necessarily wise (or even healthy). Proceed cautiously. If you can build allies, it may help.