CGPA TO % CONVERSION

I chadalasuman had done B.Tech at NIT Calicut in 2010.During my graduation period (2006-10)no CGPA to % CONVERSION was followed. But from 2012 onwards NIT CALICUT has been following (CGPA�10)-5 Formula.Earlier students before 2012 had received a copy from NIT CALICUT stating that "The institution doesn't follow CGPA to percentage conversion.Hence CGPA can be directly converted to percentage I'm not offending the university for following the above conversion formula. But in 2015 march the Senate had passed a resolution that the current conversion formula will be applicable to the old batch students. This decision with retrospective effect has made me ineligible for IOCL and ONGC interviews scheduled on 9-06-15 and 17-06-15 respectively. Some of the old students(prior 2012)were also affected by this for various other purposes. Based on this can I file a PIL in HIGH COURT.