Registry date deliberately passed by the seller on a disputed lan

I was purchasing a land in which i had paid 25% amount to the seller at the time of agreement,i agreement the registry date was decided of 30 april 2017. I had applied for loan through bank for which bank was asking the Aadhar card and bank statement of the seller to disburse the loan amount.i asked the seller to give their required documents for loan disbursement on 25 april but they only provided the bank statement not the aadhar.On 26th april i also got to know that there is a dispute on that land also.i was trying to contact the seller about the dispute as well as for the aadhar card but they didn't responded.Finally bank contacted me again on 2 may 2017 to provide the aadhar card of that seller, (why on 2nd may beacuse on 29th and 30th april,it was saturday and sunday) and i called them for that aadhar card they denied me buy saying that your registry date has gone passed so neither i will go for registry nor i will pay back you the booking amout at the time of aggrement. Now waht to do? kindly suggest rgds