Builder lack of transparency

I had booked a Jodi flat in one of the projects. One of the flat out of that Jodi flat was under subvention. I had disbursed around 27 lakhs for the subvention flat in dec 2021. I got the reimbursement cheques in the month of April worth 4.5 lakhs which was equivalent to preemi interest for 3 years for 27 lakhs disbursed. Now I had caught 2 calculation mistakes earlier which the builder rectified after long correspondence and I had to show him every proof. Because of that I had doubt on the builders ethical practice. So I demanded a full calculation on how he came to the figure of 4.5 lakhs as my preemi interest and demanded the detailed calculation as I doubt there is calculation mistake there as well but the builder has bluntly denied to share any calculation and threatening to charge the interest due to delayed payment. I have already paid 40% for Jodi flats and currently I don’t have the confidence to release more funds due to its lack of transparency. Also builder has received commencement certificate till 15th floor and my flat is on 22nd floor and building is of 60 floor. Taking all this into consideration I am not feeling safe to invest further in the project and want my full refund with interest. Do I stand any ground to pursue this?