Builder sent interest certificate on demand, but I haven't received hard copy of Allotment letter & agreement is not registered

I booked a RERA registered flat by paying 10% of whole amount. My Agreement for sale is signed but builder didn't registered it yet. They are demanding 80% money as per construction progress. 1. Thay demanded money on November 2023 whereas I received all documents on Dec'23. And put interest from Nov'23. So no question arises to put interest from Nov'23. 2. There is a court case still pending against the project and I've never received any status from their side after multiple reminders. Still I believed them and applied for Office loan. My project has 3 blocks and the Case is not related to my block, but it is a land conversion case against the project. Land is registered as "Pukur"(pond) till now. 3. Their Allotment letter was faulty and they sent me the revised copy in April'24. So for that reason my loan application was put on hold. 4. They sent me demand letter which was faulty and asked for more money than it should be. It was rectified on Last week of May. 5. Still I haven't received hard copy of my allotment letter ! After all these they've put interest on my demanded money since Nov'23! Now my question is what can I do now? Can they charge me interest? And if yes, since which date. Next is, if I want to cancel the flat booking, how much refund I can get?