Jet Airways — refund of air ticket cancellation

My son booked a jet airways air ticket for travel from toronto to new delhi on 11th may 2019 through paytm. This ticket was abruptly cancelled by the airlines causing monetary losses to my son in two ways. He has not received the refund even after 15 months of the date of travel.. Secondly, he had to book another ticket with another airlines at the increased fare.

We have written many times to paytm customer care and even mr. Vijay shekhar, the owner of paytm and seniors authorities of jet airways but all our requests have fallen on deaf ears with no action so far.

Kindly help.