Quoted from Pinballdad:

Well. Let's suggest this then. You are both two human beings that had a deal and after parting you are not content with the representation. First thing to do is call or email him and begin a dialogue on the issue and go from there. Who knows, he may be the type of person, after you explain the imbalance, that steps up to the plate and tries to rebalance the transaction. That is what I would do. Forget this forum for now and try a direct approach first as a courtesy

Just my 2 cents