Area mismatch in title deed and patta records

Hello all. My mother had purchased a land 30 years back, and the mutation had not been done since recent times. When the mutation was done recently, it was found that the area as per the revenue records (for which the taxes had been paid) is less than that of the title deed - a shortage of of about 2.5 cents were found .. My mother says a survey was conducted while she purchased the land and was in conformance with the title deed. we actually want to sell the property now and I would be thankful if anyone can advise on how to correct the area in the revenue records .. Thanks in advance.