Myntra.com — exchange issue and no resolution provided by the company

Address: New Delhi, Delhi, 110092

I ordered a pair of shoes for which it was written "exchange only". Now when i wish to exchange it for a different size, myntra app is not allowing me to exchange it. It says pincode not servicable. When that product can be delivered to my address then why it cant be picked up from the same address for exchange?

Customer care did not provide any resolution.