There way too much at stake here to rely on opinions and advice from plumbers and DIYers. While it certainly seems like you should have some recourse, you need to consult with an attorney who can provide you with the legal advice and opinions you need. Our opinions might or might not be valid, but they have not weight or real value toward resolving the problem. Since you very probably have to litigate this in court, the sooner you get an attorney involved the better. Good luck!