HTC — I have Submitted my HTC Desire 816 at service center and not received back.

Address:

New Delhi, Delhi

Service Center :- TVS Electronic LTD 38-A Bunglow road Kamla Ngr Delhi. I have submitted my phone for replacement of screen to authorized center on 7th July 2015 and the server report mentioned return date as 11th July 2015. I tried to reach service center via phone but their phone is not reachable even wasted 4 days in calling them.. On personal visit they are saying it is not repaired due to non-availability of spare parts in India for HTC phones that is strange (executive name Manish on sevice center gave this information). I tried to reach via online chatting facility provided on HTC site but unfortunately that seems to be a fake service, I have wasted couple of ours and it is showing estimated queue time as 4 mins... Is there any authentic way to get response from HTC customer service centers.. Please suggest..