shaman didn't work
How come? I think that using shamans at lower levels should prove a lot easier than druids. Maybe you're just doing it wrong? You said you ran it up to level twenty, so just in case here are a rough way at those levels.

Before:
1. drop all searing totems.
2. lightning shield on.
3. flametongue weapon on.

Pull:
4. Lightning bolt twice from distance (don't shock) before they get to you.
5. Drop all/round robined stoneclaw totems.

-- From here the monsters remaining, be it two or three will attack the totems and you can pick them off one-by-one. It does work if you do it right. I cleared all dungeons up to heroics content with 5 elemental shaman with gear from mid 70s on all.