Reduction in employer's contribution to social security scheme

Background I work in an autonomous organization under the Ministry of Information & Broadcasting, Government of India. Most employees of my organization have been enrolled under the Employee’s Provident Fund Scheme. So far, our employer has been deducting 12% of our basic salary and depositing a matching amount as the employer’s contribution. However, we have received an order that from this month onwards, the employer’s contribution will be slashed to Rs. 1800/- ( from over Rs. 9000/- presently in my case, to take an example). However, employees who have joined our organization since 2014 have been enrolled in the National Pension Scheme and they have a 10% employee contribution with a matching employer’s contribution. So the difference between employer’s contribution for those enrolled in NPS and for those under EPF can be Rs 8000/- or more even though they work in the same position and draw the same salary. We approached the EPF and asked them if we too could opt out of the EPF and join the NPS. We were told that employees once enrolled under EPF cannot join NPS. Questions Is it legal for the employer to make radically different rates of employer’s contribution to social security schemes of employees ? If not, is there any legal redress for this? Is it really impossible for employees once registered under EPF to shift to NPS even though they might get significantly higher benefits from doing so? If it is possible to shift, how can the Institution do so?