Of course you are right to pursue it. You were CHEATED, and if you let him get away with it (he is not so heimische in my book, btw), then you are actually encouraging him to keep cheating others. Take him to a Din Torah. It is YOUR $1,300. These thieves count on people like you not making a fuss, or giving up after time, so they can continue in their dishonest business practices. Shame on them, but shame on ALL of us, when we encounter someone and allow him to get away with an aveira that shows him to be just as treif as if he was eating mamesh tarfus.
I understand you just had a baby and you find this unpleasant. It is not merely unpleasant, it is dishonest, disgraceful, and despicable behavior, but especially so when it comes from someone others look at as frum.