1 A redevelopment agreement must have been executed into between the owner and the builder. Now if the builder has not honoured the agreement the owners cancel the agreement.
2. It is not clear from your query as to from whom you have purchased the flat. When the redevelopment agreement is not honoured in its entirety the builder could not have sold the flat in violation of the terms of the redevelopment agreement.
3. You should have conducted due diligence before buying the flat. If the redevelopment agreement has not been honoured then the owners can move to court to challenge the sale made to you which can result in your eviction.