On the recommendations of the Third Pay Commission, the pay scales of Punjab Government employees including that of the petitioners have been revised w.e.f. 1.1.1986 and the Government decided that besides the grant of regular annual increments, one additional increment on each occasion on completion of 8 years and 18 years of service on or after 1.1.1986 in the form of proficiency step ups be also granted (Annexure P-1). On the revision of pay scales of the employees w.e.f. 1.1.1986, the petitioners have also been granted revised pay scale and have also been granted the benefit of additional increment in the form of proficiency step-ups on completion of their 8 and 18 years of service after counting the period of service rendered by them on work charges basis. It is averred in the petition that suddenly, the respondents decided vide letter dated 9.8.1990 (Annexure P-2) to withdraw the benefit of additional increments granted to the petitioners