British gas wouldn't do a written report. The trouble is customers can hide intermittent faults and no engineer would pick it up. They can say they are safe .
We always had people phoning up after the first service saying there is now a fault , yeah of course it wasn't there before ?.
It's a minefield.
Id of thought the correct route would be to contact the installer and voice your concerns . Once youve voiced your concerns the installer should send and engineer out to inspect your concerns. Once inspected he will then either get them put right or if he feels theres no issues give you and explanation to why its been done like it as . After this if your still not happy then id bring a 3rd party in . This way will save you money if the concerns can be resolved between you and the installer
Im not a plumber but a painter and if i did a job for you and you had concerns about the work id expect you to contact me first to voice your concerns and if theres issues give me the chance to put the issues right . If you went straight to a 3rd party id be well peeved off and it would put tentions in the concerns that dont need to be there.
If you have concerns i take they are obvious and visable. Cant you post them on here or post pictures and some one like Neil Fallows who is an engineer or Dave or another member will give you advice to wether you should have concerns or not.
Like i say if id done the work id expect you to come to me before a 3rd party