Brought property but did not register other party took loan on it

Hello Sir/Ma'am, My father had bought a land in our village. we have stamp paper also citing the same that it belongs to us and everybody knows that it's ours. now the thing is that, my father didn't registered the same in panchayat and the previous owner has took loan on that land by allowing it as collateral to bank. this loan period is also like 10-15 years long and iits only like 1000 but interest has increased to 1 lac. now he is refusing to pay loan and by that we can't register that land on our name in panchayat as the land is under collateral by bank.