Hello
We had a simular problem when we bought our house, it was changed inside, however we were never told of the changes, we only noticed when the house was nearly finished, and at that stage we had exchanged contract, we had no comeback, the builder took the view that you could like it or lump it. At the time the agent know about the changes and never told us, we were left with a living room much smaller that the show house, and some of the kitchen lost, I am afraid that this seems to be fairly standard where bulders are concerned. Speak to your solicitor about the matter