Good to hear that there is a forum Chennai Kolkata Passenger forum. Isnt the time proposed almost same as its old slot? The issue here could be that SR may not want to keep this in the PF for a long time especially the time when Coromandel arrives Chennai around 5pm and same rake leaves as Chennai mail. Stabling it in the PF for 3 hrs maybe far more acceptable as compared to stabling it for more than 6 hours !!