There should be a link on every track/album to easily notify Spotify of incorrect metadata such as incorrect artist, track name, album art etc.
Updated on 2017-09-22
Quick update on this folks. We're currently testing something new called Line-In--our new metadata crowdsourcing platform.
Line-In is a tool that allows our most trusted fans and music lovers (like you) to suggest edits to the information we have about artists, albums, and songs on Spotify. This will help improve, extend, and confirm the data describing music - which will in turn help us improve experiences for Spotify Users and the Artists creating the music on Spotify.
For now, please note that if you’re unable to play a track, there could be a few possible reasons why: