I have a contractor renovating a building for me. It is a Cabin in the Upper Peninsula of Michigan. I made an over-payment of $6000 over six months ago. I caught the over-payment when I reviewed the contracts and estimates of material and labor. I also determined that there are two contracts for the same work except there was a revision that I requested. The revision was written in a different format. After reviewing those I adjusted the over-payment to $15500. I informed the contractor of the over-payments but he does refuses to consider refunding the money to me. How should I proceed? Should I simply consult a lawyer?