Stage wise payment violation, sale deed review/verification, Construction agreement pending

Hello Sir/Madam, I have invested in a property(flat) in South Chennai. I have an issue with the builder asking me to release 100% payment even before registration. I am not going into OC/CC, A Khata conversation yet. I have taken 80% loan from bank and based on the agreed schedule, bank will release the last 5% of loan amount only when the registration is done and sale deed is handed over. The bank is ready to give over the final cheque on the date of registration to which the builder is not agreeing. The builder is in constant disagreement and it's causing me mental agony. The cost of the property is less than 50 lacs(excluding GST) and already 35 lacs is disbursed. Also, till now the builder says that Sale Deed and Sale Agreement is the same though I am not sure about the exact law regarding both for the State of Tamil Nadu. Are they the same? The only two documents that they have taken a signature of mine are on sale deed and construction agreement and I don't think the later is yet registered and they gave me a future date for registering the construction agreement because now the bank is asking for it. To be frank, I asked them for a soft copy which I am yet to receive but I signed on both the stamp papers. Builder asked to pay the last 5% from my pocket and when the bank releases the money subsequently post-sale deed registration activity, they will then refund this money to me. It means I am paying 105% in advance and then have to wait for their mercy to get the return. This is deviating from what was agreed upon. The bank plans to pay the final 5% through a cheque on the day of sale deed registration and not before it, fair enough. They wouldn't budge. I have a soft copy(Word doc) but not the actual document which I signed on the stamp paper. I am sensing some issues that may creep up during the handover phase and wish if someone helps me through the legal route if required.