The bathtub has already been installed.. What do I do now?
You speak kindly with your site manager and let him suggest a solution. Answer A (satisfactory): "We will do it again and then the bathtub will fit perfectly with all connections," an email summarizing the content to the site manager, his statement in indirect speech and the addition "If I have misunderstood or misrepresented anything, please correct me." Answer B unsatisfactory: Express that you do not agree with the solution and what you expect. If there is concession, revert to option A; if not, report the defect in writing and set a deadline for correction. This is a fairly simple process.