Typical housebuilder and typical Crest Nicholson - why replace damage component when you can part bodge or repair it!
Ask yourself if you would put up with any scratches on a brand new car? Of course you wouldn't!
The problem here is the glass used by most housebuilders is cheap Eastern European glass that is softer and more easily scratched. They can hide behind the Glass and Glazing Federation guidlines and the NHBC "A Consistent Approach to Finishes" which states:
GLAZING 1.2 - S5 Glass shall be free of undue defects.
The following are acceptable if they are neither obtrusive nor bunched:
- bubbles or blisters
- hairlines or blobs
- fine scratches not more than 25mm long
- minute particles
The above does not apply within 6mm of the edge of the pane, where minor scratching is acceptable.
Commentary
- glass should be viewed in daylight from within the room and at least 2m from the panes (3m for toughened, laminated or coated glass) facing the glass.
Obviously on a sunny day the scratches may be more likely to be visible than on a cloudy day.
As for scratches to be inaccessible, how are the windows to be cleaned? Why cant scaffolding be re erected.
As for some of the panels cannot be replaced anyway" you have better hope they never get broken then!
Clearly you are being misled to put it mildly.
Any glazing specialist or inspector will no doubt be conservative on what should be done, and what can be done (cheaply) to resolve this, especially if Crest are paying for their time and report!
As for the cause of the scratches:
1) Protective film should have been put on the glass at the factory (but this would have cost Crest Extra!)
2) I suspect your home is rendered and the scratches are from the cleaner removing splashes off the glass.
3) They can also be caused by the painter using glass paper on frames or walls or the cleaner using a blade to get paint off the glass.
All in all your problems are due to a general lack of care in building your home.
Exactly what you would expect from a 4 star rated housebuilder!
In all likelihood scratched glass wont be your only problem!