pay related in govt job

This is related to govt job in punjab. In Oct 2013 punjab govt advertised 461 new posts of inspector in the department of food and civil supplies punjab. Pre entrance exam took place in DEC 13 and mains exam in Jan 14 . But there was writ and appointment letters were not issued to successful candidates. The high court gave the verdict of conducting the main exam again which was reconducted on 7 DEC 14. Meanwhile in December 2014 Punjab govt passed new rule that new govt employees of punjab govt will get only minimum basic pay(10300 in this case) for 1st 2 years which was implemented from 15 Jan 2015. The inspectors who were selected finally got appointment letter on 2 Feb 2014.But in this appointment letter the department is offering only minimum basic pay i.e as per the new notification of punjab govt. My query is that can we go to the court and claim that we should be given pay as per terms that existed at the time of the advertisement of new job which was published in DEC 2013.At that time the new recruits of punjab govt were getting all the perks I.e basic+grade pay +da+ hra etc from the very 1st day of their joining. What are our chances of wiining and getting full pay?