Need advice on delayed possession..

Booked flat in one of the under construction property in thane area. Possession date was dec 2023 as per agreement but builder got extension from rera till dec 2024. And its 2025 and still we are waiting for possession of the flat. So basically there are 3 towers in that project No. 1&2 have only 2/3 BHKs and tower no. 3 contains 1 BHK apartments. so builder first got permission to extended floors of tower 1&2 from 33 to 37. Then he asked RERA to extend possession date by one year and he received the same and no consent was taken neither he bothered to inform all residents who has bought property already. This is how they are fooling customers. They know all the loopholes.. now they have planned tower no. 4 in front of tower no. 1&2 blocking view of all which was never planned initially! Be aware and research thoroughly before purchasing the property! What all options are there legally so that I can file a complaint.. looking for advice..