Builder demanding full payment stating fit-out, while building OC/CC/Work still pending

Hi, Would like to know, we have booked a flat in 40-60 plan, where it is been mentioned that 60% to be paid at the time of possession. But builder has issue a letter to clear pending 60% as fit out, stated that after clearance of payment pending work will be cleared in 75 days. When we visited the building, can see : 1. Lift not installed. 2. Lobby work is pending.(Tilling and railing) 3. Paint & putty work not started. 4. Amenities not ready at all. 5. Flat tiling/ paint/putty/electric work not done. 6. Building sewer work not done. 7. Final demand letter issued without any due date. 8. Getting repeated reminder emails (as some person has paid 95% as 5% held by bank still sending reminders) 9. some banks also in this case issue 100% payment. Is it legal? When we asked OC/CC, no proper revert been given. When we asked statement of account, no proper ledger been shared. So in this condition can we approach to rera or consumer court? As per RERA project timeline is Dec'23, but demand raised a year in advance, should we pay or can hold payment without worry considering he is on default?