I had a very different experience with National Grid. They were working in road outside renewing pipes for the street when they knocked on my door & told me I had a gas leak.
Oh my goodness I said, can you fix it? (I was more than happy to pay anything to be safe!) They said a flat NO, all we can do is cut you off, you will have to arrange your own repairs.
Could they recommend someone? again NO - go through the Yellow pages I was told.
So thats what I did but on one could come out for a couple of days so sat in a freezing cold house for days worrying myself sick.
I would have been more than willing to pay them, but it was their lack of concern & unhelpfulness that upset me.