Revised gratuity

Sir I was working as a staff reporter in a Tamil daily 2002 June to 2013 january. I was resign my job in 2013 January. I has been received gratuity amount in April 2013. After my resignation my last drawn salary was revised as per majithia wage board. But the company refused to give revised gratuity as per majithia wage board. I ask revised gratuity to the company through many letters. But no reply from the above company. Now I am file form N in labour commissioner. The enquiry will be start in next month. Please experts describe the rules about revised gratuity?