They're the only ones who have ever worked on my boiler!
I wasn't there for the service from Malcolm Plumbing & Mechanical this time, but everything seems to be working. Last year after the annual service there was a problem. But this year there doesn't seem to be any problems. I've been using Malcolm Plumbing & Mechanical since the eighties when I moved into this house. In my opinion, they are quite expensive, but there are the only ones I've ever used.