India Post — Non delivery of registered post to taiwan

Address: 600053

Website: www.indiapost.gov.in

I have sent an envelop to my friend in Taiwan on 27th Feb, 2017 by Register Post via consignment no. (RT[protected]IN).
The envelop has not yet been delivered even after 3 months. I have reported this to India post and also written complaint to the post office authorities in Ambattur branch, Chennai. On tracking it shows that the item has been dispatch from KOLKATTA AIRPORT SORTING DIVISION, there is no update thereafter. We have followed up with Post office in Ambattur post office, KOLKATTA Airport sorting division but nothing progressed so for.

Please help us to track the envelop or compensation in case if it cant be traced.