Aye, Gas Safe plumbers are a lore unto themselves, I know 3 personally and even they are a bloody nightmare to actually get to turn up, one stood me up one afternoon, rebooked for the next morning, stood me up again, rebooked for the afternoon and stood me up again. Finished up calling 2 weeks later to see if I was "about" as he had a free afternoon.
The best bit? I went to school with his daughter, Ive know him and his family for about 30 years. What hope have you got with a random plumber?