First Flight Couriers — missing my 1 bag from the parcel

Address:

R.H.O 408A, vishal bhawan,95, nehru place, new delhi, New Delhi, Delhi, 110019

I had courier of 11 kg of clothes which was couriered from first flight delhi office personally by me. It had 6 bags of clothes which were packed by uttam singh ([protected]) from delhi office staff member. He has delayed our parcel from 13 to 18 of march 2019 and later without asking us he has transferred from flyking courier service, which is not appropriate. I just received my parcel from flyking yesterday and i have lost one bag of clothes from the parcel which had 5 pair of jeans. Please do whatever is possible to help us with our loss which was worth 6500 inr.
Uttam singh on phone conversation is taking it lightly and saying us like "it's ok aapko jo case krna he kro hamare waha se nahi hua he loss" and not willing to take any kind of responsibility because i personally know he packed in front of me as such parcel was packed in bag with stiches in front of me. I had 9 pairs of jeans which also i had written on parcel bag.
Tracking i'd d991m0689989 which also i was not able to track. Tracking id from flyking is[protected].