What is impact of not having wet land conversion certificate?

I have bought a flat 6 years ago in Nayabad , Kolkata. The building was a joint venture between a promoter and a land owner. The property has legally sanctioned plan and the flat also was registered under my name. But till now mutation and completion certificate is pending . Recently Corporation has sent out a notice saying that the building is built on land type bil ( small wet land) and they are asking for the conversion certificate . Failing which , they will take stringent action. Promoter is saying that they have all necessary documents except the conversion certificate as that was necessary during the time building was built. So they are asking us to wait till the time they take any further action . They are assuring us that they will move to court , if necessary Now, the questions are : 1> What actions could corporation take now? can they demolish the apartment now where 5 families are already inhabiting. 2> What should we do as flat owner ? 3> What are the legal ways to resolve such issues . ? 4> What is the rule of conversion ? can the landowner convert the land now ? We are in deep trouble and not able to understand what should be the course of action . Please advice.