Myntra.com — Order cancellation but not responding

I got my order but due to some size issue. I cancelled my order and tried to return that order but there's no option for return because of delay updation of app so I clicked that cancel button but now I can't able to return this
"Myntra app showing me that your order is not arrived yet sorry for delaying.
They're also showing we're trying to cancel your order." But when?
Now it has been 15 days since I complained about this issue but they always say please wait for 24hrs and 48hrs but they don't resolve this issue.
I don't want this over size t-shirt and I want my money back. Please do something as soon as possible