Pending registration of the property deed and proving onwership

My father bought a property from my neighbor in 1998 in Kolkata. Total area was 4 kottah and he sold 2 kottah to my dad. However in those days there was a system that you could pay a part of the total registration stamp duty and go for registration. The registration was done and entry was made but remains in pending state unless the remaining amount is paid. Now in our scenario we paid half the amount and kept the half amount due. And we never paid that amount and my dad never claimed the original deed from the registrar office. Now the son of my neighbor suddenly came and saying that his father has never sold the land to us. Now we have just a xerox copy of the deed and mutation certificate of the my property. We have also lost the receipt to claim original deed. We have xerox of that and a police GD copy that we lost that receipt. However in West Bengal registration web site I can see that my father name was there along with deed number and land details in legacy deed section and and in deed details the date of completion is showing 2015. Now my question is : 1. How can I get the original deed from the Sub registrar office. 2. How to prove ownership of that land Documents we have currently a) xerox of property deed, b) original side plan, c)xerox of the receipt to claim of the deed, d) KMC mutation certificate e) Police GD copy for the lost reciept Kindly help me and also please provide contact details so that I can contact in person with you.