Jeff. If you lived in Australia I would complain to the relevant Building Authority. But you give no indication of where you emanate. Why not put in a claim against you Houshold insurance & let the Insurers find the culprit?
If you called in a Licensed Plumber to find the problem he may have to excavate to find the problem, fixing the may be part of the reinstatement but most would be covered by houshold insurance provided you did use fully Licensed persons to carry out the reno’s, if not all cost will be borne by yourself.
Another reason to only employ fully Licensed & master Plumbers.