You human Warden, are very confusing. Hissra understands little of what you are even saying.
Lalin, Hissra understands what you are recommending, and there is a sense to it. However, what would be our reason for approaching these... middle men as you call them? They will assume we are looking for them. I do not believe as the human does, that they will believe that Grey Wardens would be involved slavery in any way.
If you claim that you are Wardens, human, they will immediately be suspicious of you. You are a member of a society that persecutes people who break the law. It is much smarter instead of play it that we are mercenaries. This way it is not so strange we may be approaching them for another reason, perhaps trying to blackmail them, threatening to expose their little slavery ring if they do not pay us, or somehow deal us in on the action.