A while ago I wrote the above message.The plumber has returned, last week, and cut into the cement exposing the pipes around mixer and the place where the feed from the mixer with the temperature regulated water comes out from the wall and to which the shower tubing is attached. He maintains that there is no leak as these are the only bits where a leak can occur and they are dry, and he says that is they way he found them. I do not know if it is true he found them that way.
He maintains as there are no connections/joints in the places where he has not cut in to expose the pipes he installed, there will be no leaks in those areas. However the outside wall has a damp stain larger than ever and does not seem to be shrinking.
My thinking is:
a) If he found the leak and fixed it surruptiously the patch may still grow for a period of time - time will tell.
b) If he has not found a leak, the leak is, must be, in the pipe where he insists a leak cannot occur due to there being no connections, as it is just pipe.
As you can guess the relationship between the plumber and me is to say a bit fraught. His behaviour suggests to me he does not like being accused of producing defective work and so would not, possibly, admit to finding a leak.
He wants to know tomorrow if there is any water on the bits he has exposed, which there isn't. To me that is the wrong question. It should be after a further period of time is the patch growing or shrinking?
Any advice on how to proceed would be much appreciated.