Occupation Certificate of condominium and Apartment owners association

Sir/Madam, I have purchased an apartment in a resort in 2008, which is used as resort and developer had advertised that the apt owners will get 6% p.a. as rent back. virtual possession was given in 2011 and the key of apartment is with the developer as he is renting it out. No rent back paid until 2018. then in 2018 he asked us to sign L&L agreement with revenue sharing. they paid small amounts for abt 1 years then it stopped. Now he is asking us to pay maintenance and utility charges and taxes from 2011 while the apartment was used by the developer. Please advise what we have to do to get our rent back or our apartment back after clearing all old dues? When the investors/apt owners requested for Occupation Certificate, the developer said the below: "We are of the opinion that since the property in question was constructed and completed prior to Notification of 2013, the process for obtaining Occupation Certificate prescribed vide said Notification of 2013 did not apply to property in question" Kindly advise on the above two aspects. Property is situated in Neral, Raigad district, Maharashtra. Thanks,