Problem with an incomplete/truncated music track bought on iTunes Store

I've just bought an EP from the iTunes Store: World Order - Let's Start Ww3.

Track 5, 'Singularity', ends abruptly. It is not a quick fade out - it stops mid-song, halfway through a line of lyrics. At 2:16, it is the shortest track on the EP.

HOWEVER, 'Singularity' is also available in the iTunes Store as a single - and the single version is 4:30 long.

This seems to indicate an incomplete version of the track was included with the EP release.

Where the heck can I report this?!

Thanks