This also happened to me a few months ago but I fixed it quickly enough.
I was at work and wanted to buy something from the webstore, and when I went to check out, it said my primary CC was gone. So I tried to add it back and got some error. This was before the official Remote Play app was out, so I used my BlueStacks android emulator and tried to remote play to my PS4 from work and when I did, there was someone playing Star Wars Battlefront!
I was freaking out, so I quickly went to his friends list, wrote down the PSN name, shut off their PS4, and looked up their PSN name and saw it was someone in Russia.
Changed all my passwords and added as much security as possible, reported their PSN name (nothing came of that of course), and no problems since.
Good luck with your endeavors and I hope you get it resolved soon.