So I'm having some problems here. My pets are levels 33 and 34 but I can't seem to beat the group with a level 30 undead arch mage (4 stars) and at least two level 30 undead knights (3 stars). I'm pretty sure a third knight pops up when the arch mage dies.

Any suggestions??

Well your gear and stats points are kind of all over the place.. I would suggest focusing on building your team. I started with this guide:

http://www.sylestia.com/forums/?thread=1898#2

but there are plenty of threads in the forums about different builds that work well.