My mashups on mp3 distribution websites

These are content grabber sites that use your stuff illegally. Some not only grab from Soundcloud, but also Youtube etc.
After grabbing some of them will even try to screw you over for paying them, as you are using unlicensed music etc. (which may or may not be true). One of those once tried to sue me about copyright infringement about a song I WROTE… so imagine.
Hence you should inform at least Soundcloud.
While it is to some degree publicity they are breaking laws.