Spice Jet - No refund of airlines cancelled ticket

I booked two round tickets Hyderabad to Madurai (**-*-** to **-*-**). Spice jet cancelled the flight due to its operational problems and offered a full refund on **-*-**. Upon continuous chasing assured refund within **-** days. But even after ** days and three reminders, no refund was made. Failed to understand why so much time is required for the refund when they had cancelled the flights.