What can I do if a builder is delaying in handing the project?

I purchased a flat in under construction Project in Bangalore on 15-06-2018. Property Cost is 81,75,034 I have already paid 7,17,529 from my pocket. Agreement done and I took a loan for which a tri-patriate agreement was done and I took the first slab wise payment upon the ground floor slab for 17,93,824/- in July 2019. which the bank paid to the builder. I paid TDS also for the same. Original handover date was in December 2021 but due to covid the builder took 1 year extension from RERA and the new handover date was December 2023. But now the builder is saying that, they will be able to complete the project only by 2027 and they are willing to accept cancellation and will give refund. The question is that, I have paid the EMI from August of 2019 till date and the maximum portion is only interest payment. Should the builder give a refund for the interest which I have paid on home loan and also what % of the interest they should give me for the down payment which I have made.