Flipkart — Cancellation of exchanged order by Flipkart after the return period is over

Address:

Flipkart Internet Private Limited, Ozone Manay Tech Park, #56/18 & 55/09, 7th Floor, Garvebhavipalya, Hosur Road, Bangalore – 560068, Karnataka, India

Hello there. I was using flipkart for more than 3 years but recently they tricked me. I ordered a pair of shoes but the size was too big for me. As no other sizes of the same colour shoe was available so I waited for a few days. At last two days before the expiration of the return period, I decided to go for smaller size of different colour and placed an exchange request. The exchange order was placed successfully and it reached my nearest delivery centre after a few days.
On the next day I got a sms that my item was out for delivery but it didn't reach me. No delivery agent contacted me. I thought that it has been rescheduled to the next day but it didn't show up. After 3 days I got an email that my exchange request has been cancelled. I called the customer service and they said that I myself had cancelled the order! Why will I cancel the exchange request after expiration of my return period. Now I can't return nor wear the shoes.
Please help me.