Length of service for calculation of gratuity

Sir, In my case of Direction for Payment of Gratuity ( Form N ), the Controlling Authority has considered number of years 11 instead of 12. My Date of Joining is 09/09/2002. Date of verbal termination is 20/08/2014. From 12/03/2014 to 19/08/2014, I was on LWP because of orthopedic surgery i.e. Temporary Disablement. The judgment does not consider this period because the total working days in the last year i.e. 12th year is less than 240. As far as I understand, as I have completed more than 5 years of continuous service, in the last working year if the period is greater than six months, then it is taken as full working year. Even if the LWP period is not considered, the total Length of service becomes 11 years 6 months 3 days. So again my full working years for the calculation for Gratuity should be taken as 12. Kindly clarify whether my Total Length of Service is 12 years or not? If yes, whom should I approach for the appeal? Within how much period? Do I have to deposit any amount with higher authority for the claim of 12-year gratuity? Thanks.