PayTM - No refund of cancelled Indigo flight during May 2020 lockdown

The Indigo flight from Bangalore to Dehradun on ** May **** was cancelled due to nationwide pandemic lockdown. The airline returned the refund amount to PayTM (from which platform the ticket was purchased) on July-August ****. The Paytm sent me mail on ** Jan, **** acknowledging refund and initiated the refund of Rs **** to be processed within ** hours. Almost * months have passed but the refund is still NOT completed. Even after so many phone calls and chats they are reluctant to refund and intentionally delaying the refund. They are enjoying the interest and whenever I called up them they were lying. Kindly initiate legal notice to them.