write a letter/represent for the legal case in small claim court

I need to urgently write a request to the opposite party for the small claim court in Cambridge, Massachusetts, US.

Please, indicate the experience in writing these letters, maybe an example.

Ideally, I would like also to find an attorney who is available on June 9 in Cambridge, MA

Brief for the case:

The contractor was able to dramatically reduce the work needed for new water pipes to my house by using much shorter pipeline - by at least 4 times. However, he still asks for practically the same amount of payment giving only $500 discount from about 8 K requested payment. Preliminary he verbally promised that if a city approves the short pipe the payment will be about 3-4 K. The city approved the short pipe but the contractor denies his verbal promise. He is taking me to court. He does not want to give the list of his expenses prior to the court, so we need to get them from the contractor