Jobs discription and not get jobs as described and harrasment

Yr I am a govt servant ...in central water commission , snow hydrology division Shimla appointed as a skilled work assistant some time before it a khalasi post...but now known as SWA when I get this job named as skilled work assistant , in our office there is lacks off regular staff and we are working on that post ,generally we are not getting salary as we described in our job offer letter ...but we doing the same many of our senior officer tell us "only" verbally that you are khalasi's and actually your job is to cleaning office and brings tea for us if you don't do the regular work as we want than you do the same like cleaning etc , if we refuse to do the same than all the seniors get on a one side and do complaint to high rank officers and employed us to the high interior place....this is the main story , nobody support us and nobody with us to fight ...even our work association cause we all are under workcharged employee...and seniors said if you do something than we surpluses you you and you all are work less...