Patta mismatch with fmb

Hi I have registered 2 plots as per sale deed 1800 sq ft x 2. FMB Shows 12 boundries and quantity in meters is reflecting correctly as 36 x 9 or 3.4 Are but the total quantity mentioned in FMB header and patta is only 1.7 Are. This is in Cheyyur taluk, near kalpakkam Any suggestion how to get this corrected? Any Chennai lawyers who can offer service to fix this for a fees.