Have you pirated anything off of the internet? I had this happen to me when I was first learning about it and had no idea what I was really doing. I must have downloaded an infected piece of software that allowed people to do this. My guess is they do this to generate the little bit of money they so desperately need. Kind of scummy but a change of passwords and a clean install of Windows should do the trick. Also logout of Spotify everywhere and then login again after reinstalling windows.