Layout of the garden changed for under construction house

Hi,

We have booked an under construction house which is due for delivery in few months.

Today I checked on the builder website that garden layout for three of the neighbouring houses has changed. As a result garden of one of the house is cutting into one corner of our garden and we will loose some area as well(emailed the selling agent to confirm).

The layout, which was uncut i.e rectangular, was one of the primary reason why we booked the house over the other options. This was shown to us at the time of booking, was on the website and many other email communications. We have already signed the contract and are shocked to see such changes and that too without any communication.

The contract did not had the garden layout but in one of the emails EA told us about the approx garden size.

So we are wondering if builders are allowed to make such late changes and what would be our options to protest the change?

Thanks