You don't name the housebuilder which is useful to those others reading your post.
From the photos it looks a bit Redrow to me.
The small gable on the garages could easily be taken down and rebuilt.
There are no "tolerances" for different colour brickwork, it is either acceptable or not.
You are 100% wasting your time reporting anything to the site sales.
Write to the construction or managing director of the regional office and send a copy of your photo!
I doubt the weather would have got hot enough to dry brickwork by February so by the summer it may be too late.
The least they can do is get a specialist contractor to tint the bricks so the colour difference is less noticeable.
PLEASE HAVE YOUR NEW HOUSE PROFESSIONALY SNAGGED AND INSPECTED BEFORE YOU LEGALLY COMPLETE