Bank employee's pension rules

Public sector bank employees , in last 20 years , were twice offered scheme wherein they were allowed to shift from Provident Fund to Pension facility at the time of retirement. On such switch from PF category to Pension category, all PF balance ( employer's contribution only) of a employee is transferred to Pension Corpus Fund maintained by each bank individually and employees stops getting employers part of PF on such switch from PF to Pension. Bank continues to deposit amount equivalent to PF ( employers contribution) to such Pension corpus till the retirement of a particular employee. On his / her retirement, pension is paid out of interest earned on such corpus fund. So far nothing wrong and a fair arrangement for the benefit of employee. However, on the death of the employee after his retirement, his / her spouse gets pension which is reduced by about 60% from what the employee was getting at the time of his/ her death, whereas amount in corpus fund kept on his/ her behalf continues to earn same interest indefinitely Further, on the death of both employee and his/ her spouse, part of corpus fund retained in the corpus fund is not paid to the employee's legal heirs and is confiscated by the concerned bank. My question is : can I challenge this arrangement in court of law ? .