Builder demolishing approved building parts — is that legal action?

Urgently seeking advice regarding a building with A and B wings. The first Part OC was received in March 2021 — A-Wing up to 7 floors and B-Wing up to 12 floors. The second Part OC was received in October 2022 with significant changes, converting the residential building into a residential-cum-commercial structure without the consent of some buyers. Under this, A-Wing was extended to 12 floors. Now, the builder plans to construct a new C-Wing and intends to demolish the already-constructed cantilever refuge areas on the mid-landings of the staircase in A-Wing (between floors 7/8, 9/10, 11/12, and 13/14) to make space. We’ve been informed that this demolition proposal came from the Deputy Chief Fire Officer (Dy. CFO), though this seems technically and legally questionable. Can the Dy. CFO suggest such demolition after approving the Part OC with refuge areas? Is it legal for the builder to demolish parts of the constructed building post-OC? What are the implications for residents, and how does this align with modifications in the development plan for a new wing?