Answers

Windows and doors are the largest culprit in lost of energy efficiency. It may not be the cheapest option but will provide you with the largest impact.

Contacting your local home improvement commission is your best recourse to start, since they typically have a fund to pay for a attorney for you if needed. They can provide mediation between both parties in hope that a court battle can be avoided. They will slso decipline the contractor if they side with you, and no contractor wants that on there record.