Spice Jet - Refund issue

Dear sir,
I have booked my flight from madurai to dubai on *'nd december at spice jet airlines by makemytrip.com portal. My travel date is ** Dec ****.
I went to airport on the same day and waited from monring to evening. They had delayed the departure time due to some operational issue.
Later on they have adviced me to reschedule the flight on next available date. So i plant to travel on ** Dec ****. So the spice jet representative changed the travel date as ** Dec **** but company didnt agree. within ** minutes i again went to spice jet's desk immediately and ask them to cancel the ticket and proceed full refund. They agreed the same.
They have wrote full refund at top of the ticket paper and sealed the bottom as well. They said, I will get refund within * working days.

I raised the complaint to makemytrip.com at the same day and ask them to proceed the full refund from airlines.
One of the respresentative from makemytrip called me and said 'full refund is not possible because you have chaged the travel date'.
I told that i already cancelled the ticket at airport spice jet's counter and i have the hard copy of the sealed ticket in my hand but they are saying airline not responding properly.

I came out from the airpot only because of spice jet staff's assurance.
She also wrote full refund at top of the ticket paper and put seal as well. Kindly help me to get my refund.
I herewith attach ticket copy for your kind reference. Also i am ready to provide necessary documents upon your request.