Pension

I am working in RBI,Ahmedabad since last 35 years. All the employees were offered pension in lieu of CPF three times during 1991 to 2000. Due to higher rate of interest in CPF and very little amount of family pension, around 2000 employees all over India did not opt for pension. Now in 2001 bank amended some basic rules/regulations of pension.the requirement for full pension was reduced to 20 years from 33 years and amount of family pension was raised to 21000 from 2700. Now after three wage settlement after 2000, pension amount have risen in thousands while CPF amount is around 20 lacs for senior officer. It is very difficult to survive on the interest of such amount. Our associations have been requesting bank to give one more chance to opt for pension to such non optees but bank is not in a mood to accept the demand.bank has huge pension fund of about 15,000 chores and bank is governed by its own pension rules as it is a autonomous body. My question is as bank has amended basic rules for pension and family pension,we should have been offered one more chance to opt for pension. What are the chances for getting pension if we move to court of law in the circumstances? Please advice. RBI employees