Air Costa — air costa refund of cancelled ticket

I booked a flight ticket for vishakapatman to hyderabad from easemytrip website for with pnr no: 02szm4 and travel dated march 3rd, 2017. The flight was cancelled with the reason saying 'cancelled due to operational reasons'.

I called the easemytrip and aircosta customer care and they said that the refund will be processed with in 7 days. I waited for 7 days and the refund was not processed. I called them several times again and the customer care executive kept postponing the dates of refund. I emailed aircosta for the refund even they kept giving me dates saying it will take 15-20 business days. Its been 6 months now that i have not received the refund.

Can you please help me out to get the refund. Much appreciated fro all your help. I hope this will help me out.