Playlists being deleted and replaced

[Munda]

Over the last couple of weeks at random times (twice within the last 20 minutes) all of my playlists get deleted, as well as my saved songs. They get replaced with playlists and songs by some artists called Niska and Ninho. Also the app keeps trying to play on a device named sm-j320fn which seems to be a Samsung phone. No one on my account has a Samsung device. 

Does anyone know what's happening here? It's really time consuming to have to log in, recover my playlists, delete these new ones, and delete the 30 odd songs that are suddenly saved to my account. 

Move tried changing my password so I'll see if that helps, but I'd still like to know what's going on.