[I never expect something for nothing...I have also said that I am going to pay it - at the end of the day he loses out on thousands of pounds of work - his problem but I can't be bothered with the arguments. He also at no point has gone out of his way you obvioulsy didn't read the whole thread there is no need to be rude, and he has certainly charged me more than an hours labour.
If what you say is true i.e. he connected a gas appliance without conducting a tightness test, and it gets even worse as that connection then leaked, he needs to be retrained and reassessed and should be suspended by Gassafe until that happens. If a DIYer did that then all hell would fly and people would be calling for him to be prosecuted. Gassafe have a procedure to investigate this sort of thing and to protect the next consumer it should be used.