1. Now a days the flats are constructed based on pillars and there is hardly any load baring walls,
2. See the brochure or the agreement for sale wherein the clause of not changing/altering the construction might have been mentioned,
3. however, the authority may pick up issues to refuse giving OC to the builder and such breaking of wll may be an important weapon to arm twist the builder for making some gain,
4. So, it will be prudent on your part to wait till the builder gets OC,
5. It may take any thing between 1 month to year depending on how your builder is pursuing the matter with the authority.