Guru Nanak Dev University — confirmation about implementation of a notification retrospectively

I am working as an assistant professor on regular basis since 15 july, 1998 in a college affiliated to gndu. As per rules i was to be promoted as associate professor w. E. F. 30 june, 2013. Inspite of my repeated requests, the college office did not accept my application for the same. Then in 2015, i was told to apply as per the guidelines of 2nd amendment o[censored]gc. After completing the api score, i applied for my promotion to associate professor w. E. F. 30 january, 2016. But the college and management authorities delayed my interview which was finally held on 7 september, 2019. During the interview the vc nominee declared me ineligible on the basis of letter no[protected] dated 26 march, 2018. How can a letter dated 2018 be implemented for a case of 2016? I want to enquire about this.