Clarification on the amount of gratuity paid to IT company employees

HI,Sir,it is with respect to gratuity payment by the IT companies,where the basic is very less and they dont have DA component,(in place of DA they have special allowance)where both are taxable component, if the DA of of 5% of ctc /companies dont give much of benefit,but they keep the special allowance-(is it not mandatory to keep the component of DA for the private employer in india,or is it applicable for the govt employee....in this situation the private employee hardly get any gratuity amount after spending a good time with the company...is their any legal recourse or public interest litigation could be filed,then what would be the process.