I learned on my first motor build, (not DNE) Quote in writing. That is the only way you have legal action. And on that quote you have on there when you sign that all changes are to be in writing too. I had the same thing happen to me and the diference was 2 times the amount agreed upon and I was just a poor kid and that amount of money was hard to pull together in a short amount of time. Sorry to hear about this. Good luck.