Builder not returning money

I have booked the flat from of the reputed builder in Dombivli (Thane/Maharashtra) in march 2018 in 22nd floor, total floor of building is 23. But in 2019 mid they have got permission for only to built 20 floor and informed me in after 6 month In December 2019. So they have offered us to take your money back or remaining flat available in building or move to the ready possession flat. We choose option to move to the ready possession flat and informed us to flat transfer it takes 3 months from cancellation time. So they have cancel the flat. everything is written on email. In November 2019- November 2020 still they are informing us we are in process to transfer the flat.For every time when we send mail to the builder they have informed us we are in process and due to covid it take delay. So finally we decided to cancelled the flat in November 2020 and got cancellation approval from builder in December 2020 and about to money back it take 90 working days time. Now suddenly yesterday builder have informed me we will not give your money back you need to moved to the flat. But i don't want to buy flat from him because they are cheated with us from last 3 years. Kindly suggest.