Delhivery — Issue With delivery

This is related to delivery of important package from bank with tracking number[protected].
As per tracking, package was supposed to be delivered on Sep 3rd, later got pushed to Sep 4th and now, it is showing Sep 5th.
Interesting is dates for all the past transactions like picking up, arriving to location dates are continuously getting changed. So, when I look at the tracking each day, there is no delay at all.
1. How can Delhivery change the date of actual transactions that is already taken place?
2. No contact number to reach Delhivery. Also, no response to emails that is being sent.

This is completely unprofessional behaviour.