Goibibo airlines And AirAsia - Refund credit voucher not issued

I had booked a flight vide PNR H*WEHQ to travel from Delhi to Melbourne on ** Feb. and return on * April, ****. But the return flights were canceled by the AirAsia airlines. As announced on their website Credit voucher will be issued for the equivalent amount of the ticket. I requested Air Asia for the same but they informed that I should contact the travel agent through whom ticket was booked which is Goibibo in this case. I have been requesting Goibibo for the same but they are just not responding about this. They have just issued the credit voucher for Rs. *** towards their convenience charges and there’s no mention of credit voucher for the amount of Melbourne- Delhi flight ticket.