Procedure to buy plot/vacant land which is in bank pledge for education

Hi, I am planning to buy a land where the seller pledged the document for the loan taken for education. In EC I can see that the document is with Bank. Now we have an unregistered agreement signed by both parties and Seller asked me to pay cash for clearing the loan before registration. Hence Please let me know what are all the legal or safe steps to be taken to pay amount and get the registration done without any legal issues? As you know while doing the registration we will buy stamp paper only for GOVT guided hence 1. What is the process/clear steps for paying cash in advance before registration for releasing docu from bank? 2. While handing over the cash to seller what agreement should be written? 3. Will it be any issues after following the steps (from ans of Q1/Q2) for advance payment which is higher value then the mentioned amount in the original registration document(stamp paper) Pardon! if my question is not clear, Incase if i follow the legal procedure for advance payment to help seller to release document and will create any issue during the registration with GOVT quoted amount?