I am having contractor problems that includes overcharging

[Jacob Botson]

My wife and I recently hired my father in laws friend to do work on our house.  We used a construction loan to get some of our work done. One thing that we had done was siding. The contractor came over and we went over what needed to be done and what we were expecting. He quoted us $9500 for siding on our house on the bid submitted to the mortgage. I then receive a bill from him way after the siding was done for the sofit and fascia for $2600. I was never made aware that there was going to be an extra charge to include that. He never brought the charges up to me or the bank when in our contract it says a change order must be submitted before any changes can be made. I never saw anything in writing or agreed to pay more for this. Like I said earlier he was aware of the whole scope of work before submitting his bid. I am considering taking this to arbitration because I personally don't think I owe him that money. Thoughts?