Vistara — Refund not issued

I had booked an international ticket to Colombo and back in business class with the reference number KDAA5J and canceled the same on 6th January. To date, I haven't received any communication nor my refund of 62, 710 from Vistara. Their websites and apps are not working and despite repeatedly calling them since the day with a minimum hold time of at least half an hour, The customer care keeps on dilly-dallying the matter by saying the refund is delayed due to covid and will come in 7 days- Despite 7 days being passed (the ticket was canceled on 6th January 2022) and yet there is no communication or news of refund from them. I have even written several mails to them which they are obligated to reply to within 48 hours but I am yet to receive any phone call or communication from them. Kindly help.