had a recent new installation of a boiler by a registered person. Had a couple of leaks after they had left. They returned to fix the following day but again the leaks persisted so I called a plumber. He came, really fixed the leaks so thought all was good until he pointed out the flue has been sited by driving it through the lintel above the window. Is this ok??? If not what do I do next? He also said he doubts the positioning is far enough from the window. All advice greatly appreciated.