Originally Posted by Daniel Holzman
I have no idea who b & q is,
Daniel; as Bonzai pointed out, B&Q is the UK equivalent of HD in the US; big, relatively cheap, and staffed by people who don't seem to know or care about what they stack on the shelves, at least imo. Or is HD better than that?
Austin1967; this looks like a bad job and may need re-building rather than repair. One of the problems is that conservatories don't come under Buiding Control, and there is the temptation on the part of builders to throw these things up. There is even less control when these things are sub-contracted. Spreading the excavated earth back under the floor is very poor; at the very least you would expect a couple of inches of concrete on a damp-proof membrane just to seal the space from ground vapour.
As Bonzai said, try and get an independent report to give to B&Q and at least they will then know you are serious about the matter. Good luck.