HTC India — Software update and VOLTE support issues for HTC Desire 828

Address:

Kurnool, Andhra Pradesh, 518501

HTC Desire 828 Dual Sim (3 GB RAM and 32 GB internal memory) was released around June last year having android 5 (lollipop) version with a promise of the update to next version i.e., android 6 (marshmallow) as at that time android 5 was outdated and android 6 was already present and even android 7 was due to release.
The VoLte support is also lacking and the same chipset used by other company mobiles like Gionee S6, Lenovo K4 Note and Coolpad Note 3 (have the same MT6753 processor) provided Volte support with a small software update. The point here is they are way less priced than this model (HTC Desire 828).
Now as the market is flooded with mobiles equipped with Volte support and the latest android version for lesser prices (below 10 k), we can't even sell this mobile in the second-hand market. We are literally stuck with this mobile with outdated software and incompatibility issues with latest entrants in telecom sector like Jio (4G with Volte).
Will greatly appreciate your help in this regard in resolving these issues of Volte support and android version up-gradation.

Thanking you,

Regards