sounds like you got a mean bunch then. :(
well there are a couple of things i can think of.........
1.take back the regular tigers and exchange them
2.re arrange the decor(sometimes stops agression)
3.keep it as a species tank only.
4.exchange the tigers for a different barb.
i know this is not the best advise,but i can't see the
situation improving with this bunch,you
could increase the tigers(not the greens)
to more, to see if that helps however it's a chance
to take because if it dosen't help you have more fish
on your hand.