@etorreborre Couple of things:
1) I tried and sbt itself says exclude(a,b,c) is the right way
2) Besides that, the exclusion in the way you suggested isn't working. In any case- I think the best way to ask this question would be on SO, so that you don't have to repeat the answers. Off for a few days, so please give me a bit and I will isolate into non-working examples and ask on SO.