property issue

my father worked at CRPF now he is retired.
in 2001 he buyed 80 cents of land and he did the payment but due to completion of leave he went back to job.
for the resgistration of land he applied for the leave due to elections duty he didn't get the leave.
Due to the pressure from the parents my father said my grandfather to register the land on his name
my grandfather registered the land on his name.
after coming to home on leave my father asked my grandfather to register land on his name.
but my grandfather rejected to transfer the property on my father's name
literally from 20 years my father is begging for the land but grand father rejected it