If the government surveyor had surveyed the property and reported that the property is not available to the extent shown in the registered sale deed s per records held by the revenue department then you may have to catch the seller only for this and ask him to refund the money taken in excess.
Alternately you can file a declaration suit to declare your property as per the registered title deed in your possession, the revenue department will then produce their records before court to clarify the issue and the court may take decision based on the documentary evidences supporting your claim or their claim.
On the basis of the pending dispute with regard to your property yo can obtain an order of injunction against the government land acquisition authority from acquiring yor land till the disposal of the pending suit.