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Were the gutters included in a line item on the proposal or contract?
If they were in the drawing, but not in the written contract, it really doesn't matter -- what's in writing trumps the drawings. If other homes by the same builder in the same neighborhood have gutters and yours does not, you may possibly have some argument to get the builder to do it, regardless of the contract language. Good luck!
If they were included, file a suit in small claims which you may win but never collect. Give the builder a final warning, in WRITING (email or certified), that you will be going online and posting comments about your negative experience.