Well I'm glad to hear that you redid everything yourself, thumbs up. ;)
But if I understand correctly, you did use the vocals from the original (even though re-arranged)?
That might well be why you got banned, as copyrighted material is frowned upon, no matter how little.
About all the tracks on NG that feature copyrighted material:
You only need to be approved for your first submission, so those people got approved for their first track, then submitted rule-breaking work. You can always report any submissions that break these rules in the Audio portal cleanup thread.
The annoying part is that the audio moderators only have control over a user's first submission, they can either ban or approve, and that's where their authority ends. It doesn't help that some audio moderators have been hacked recently and the hacker wrongly banned and approved people.