Oh dear, when I see the words "Premier Guarantee" I worry.
In my opinion it is anything but "Premier"
It is even more important when buying from a small regional housebuilder as you have done to make sure you have an NHBC Warranty. The NHBC have strict criteria and checks before allowing a builder on to their register, so it could be Stonebridge Homes were not able to meet NHBC criteria.
Whilst their may be other reasons, from what you say, it looks unlikely!
It is a good idea to have your heating system and design checked to see it is both adequately designed for your home and that it is working as it should and has been properly installed.
I would also have a thermal imaging survey carried out as I suspect that your home could also be missing cavity insulation and other insulation.
As you have found out, if the house builder flatly refuses to cooperate in correcting defects and snags, your only recourse will be a claim with the warranty provider.
Failing that, you are looking at lengthy and costly legal action.
You may have a claim using the Consumer Code for Home Builders, but that does not cover snagging and defects but Stonebridge may be in breach of the requirements for customer service. No harm in telling them if they don't change your patio slabs you will make a formal complaint with the CCHB even if you have no intention of doing so.
I am sure over the many months to come, your post will save several buyers from buying with Stonebridge Homes.
