Restrospective changes by govt

After the implementation of 7th Central Pay Commission (CPC) our Department released further benefits due to bunching of stages in compliance to D/o Expenditure's OM. But, later on the Govt. changes their stand and issued clarification against their earlier OM and tried to scrap the bunching benefits but we folk took stay on such arbitrary stand of the Govt. from the Hon'ble CAT. Now, the Govt. is making retrospective changes in the earlier 6th CPC structure which is the base of the aforesaid bunching of stages. My query is, whether such a retrospective step by the Govt. is lawful, justifiable or acceptable in our matter and whether it will adversely affect our case.