Hi there and welcome to the forum.
I think I am right in saying that PW will not make any changes to the original design and spec pre-completion as it is too difficult and will slow down everything.
After completion they have many contractors and suppliers that will do almost anything for you. They are happy to do the work (and quite rightly charge for it) but they wont do it before.
If I am wrong - let me know as would be keen myself!