Myntra.com — defective piece delivered

Address:	Gautam Buddh Nagar, Uttar Pradesh, 201301
Website:	Myntra

I am a customer of myntra from last 3 years.
I bought ucb shoes on 3rd august, unfortunately i got the defective piece of shoes. After that i request a refund request. Delivery boy said that you need a pre approved request for the same.
As i trusted and have faith in myntra, i have thrown the shoe box.
While talking to nandini (Myntra supervisor), she behaved rudely and said we cannot help you in any way.
I have even requested her that you can ask delivery boy to check the condition of shoes but she refused me rudely.

Please help me how to refund my amount as those shoes are of no use to me and i am seriously not going to use myntra in future.

Regards
Amit