arrears not paid to an government officer since 3years..

respected sir person working for PSU and his salary was not regularised..and was not got his arrears since 2017..what action can be taken further
pls suggest

hi sir I'm nt social worker I am an officer working in govt sector..I need suggestions and I am receiving many queries also people approaching me for the same..I have completed my LLB I want to gain knowledge from master minds in legal opinion like u all sir..guide me..