Nextra Teleservices — refund not received yet

Address:

Plot No 4B, District Center, Mayur Vihar Phase 1 Extension, Delhi 110091, India

Applied for a new connection of broadband for which they took 3421 rupees in advance later on after waiting for 5-6 days in initial days of may 2020.
After that, they told me they can not install the connection so i should request for cancellation and refund.

Now, its more than 2 weeks, and i have not received my amount yet, every time i try to connect to them they commit a new date which is 2-3 weeks later.