My boiler stopped working and I booked H2 to come and inspect it. They identified an error in the original installation of the boiler (my flat is a relative new build) that meant the boiler needed to be re-hung further down the wall. It was caused by an incorrect positioning of the flues. My flat is riddled with problems like this due to poor quality work during construction + installation. H2 staff were punctual, polite, explained the problems to me and - most of all - they did a great job. If only all people who worked on boilers (and in construction more generally) had this level of pride in their work and produced work of this quality.