I have heard of them but last time we used Gasking and they were brilliant. We had a new boiler installed and they did it next day service and we were amazed t how quickly the got the new boiler in. They are getting a few good reviews around are way now.

We have used www.justboilers.com a few times now and they have been fantastic. They replaced our hot water tank and sorted a major heating failure out on the same day, for less money than I expected and were really lovely to deal with. They are a local company so I thought I'd give them a mention here.