Infrastructure Development Finance Company [IDFC] — Maturity proceeds not received

I had purchased IDFC Tranche 2 bonds which had a maturity date as Feb 21, 2021. I had written many emails to the registrar of the company but it seems they don't feel important to revert me back. I had even written emails to its courier company i.e. AVIRAL but they have neglected the emails. All the phone numbers provided by IDFC, by Registrar and by AVIRAL are useless as no one wants to pick up the calls and respond to the customers. Its been 1 month from its maturity and also since they have sent the courier. I don't think so that it takes atleast 3 weeks for my courier to be delivered.