A plumber came 7-31-14 because of leaky tub faucet. He took cover plate off at handle section of works. I had a replacement on hand and asked him to just put the new faucet in. He tried to unscrew old pipe, however it was too corroded to move. Then he cut the pipe to get it out. He installed the new cover plate, new handle. Shortly after he left, I noticed the grout in the floor tile had turned dark. As the days passed, the darling spread to other tiles. So far, I cannot whiten up the grout, even with straight bleach. I remember calling a cleaning person on 10-18-14 and telling her about the floor. Last night I heard water dripping from the tub. Water was coming from the area under the faucet, right next to the tub... not from the faucet spout. My husband took the outside access cover off and water was running from the back side of the fixture. The space between the wall and tub was wet. It is not a drip, it was running. My husband called the same plumber to come over. He came, after hours rate, and said he did not install the huge inner workings of the fixture, the part that has the shower push button on it because it did not need replacing, and the labor would have been 2 more hours of labor. He says that the leaking water is probably the cause of the darkening grout. I asked him if the tugging and cutting on the other side could have caused this problem. Of course, he said this problem has nothing to do with his previous work. I want to know if his tugging, turning, cutting could have caused a metal to breakdown in some way resulting in a leak. He is coming back in the morning aR 9 am. Water for the entire house is turned off now waiting for him to come back. I need to know if he is responsible before I pay him tomorrow. Thanks