Wrong Survey Number

Hi, My dad purchased a land of 1.10 acres. While registeration we didn't verify survery number. From the day of registration we are using this land for farming (From last 10 years)(Survery Number 67). But the land which is in registration documents is different(survery number 65), where as that land is using by someonce else. So finally what ever we are using for farming is not registered in documents. All passbooks, pahani, borewell approvals are on 65 survey number but we are in 67 survery number. Now the Sellers, who sold us the land earlier, again sold our current possession land with correct survey number to another person ( With Survery number 67). This new person is asking for possession of 67 survey number land, which we are currently farming now. We want to proceed legally on this. We went to tahasildar office and asked for survey and possession certificate by doing enquiry in the village. But tahasildar is not accepting at all to do survey. We are really worried about this, we are poor formers and don't know how to proceed on this. Is there any way that we can get correction in registration docs about survey number. What we need to do for this? Please please help us.....