Late possession penalty vs delay payment

Hi Atulay, I purchased a flat in Noida extension for which I received a final demand to pay for the possession. In final demand there are couple of things on which i have concerns and need your assistance to understand if its worth to file a complaint against the builder in consumer court 1) Possession is almost 2year late. However, builder is saying that few payments were delayed hence you are covered not to get any penalty amount. As per the contract I can see that this clause is there. But that does't make any sense that delay in payment cannot delay the possession by 2years and on other hand they are charging interest 18% for all those delays. 2) Area increased charges: They have added around 70,000Rs against it and after following up they are saying common area has increased. I have asked them to show what has changes and what was the legal need for that but they have not shared anything yet. 3) On late payment days calculation: I found a mistake in they date from which they are calculation number of days for which they have charged 18% interest. I able to cross check this only for latest instalment date as that the only demand letter I have with me. Therefore, I have asked them to double check all and send evidence that this is correct for other txns as well. but they haven't send any thing yet. But, they have adjusted the one which I found Is it worth to take this forward? Thanks