Hathway — Refund of INR 1800 not provided

I need a refund of INR 1800. I made a payment of INR 1800 for four monthly plan at Hathway site on 20rd Nov 2020, for renewal of my Internet connection. They said they will come to install in 2 days and that the router and modem devices are free (work order number[protected]W403015). For the next 4 days nobody responded for connection. I called the hathway customer care executive and I was informed that there is no port availability in my area and refund will be issued.
I submitted my complaint on 23/11/2020 to Hathway and they responded that my refund will be generated within 45 days from the date I lodge my complaint. Since then there is no response from Hathway. All the concerned people I was contacted by are neither responding on call or text msgs.
I have called customer care executives multiple times and in response they always ask for another 48 hours. However no executive has ever responded after taking even a week's time.
Now after 2 months they are asking me to return the modem of their previous connection which I had returned in 2017. At the time of installation both router and modem devices were free. Now they are asking me to show a 3 years old receipt else they would not generate a refund from their end.
Kindly look into the matter as it has been more than 70 days. Please resolve the matter as soon as possible.

ANURAG NEGI
HATHWAY A/C No. [protected]