Reebok India — Torn upper area in merely 3 months

I had ordered a Reebok Fast approach 2.0 Lace-Up Running Shoes on 6th July from Ajio. The shoe started tearing surprisingly from the upper end in 3 months and the inner foam is now clearly visible.
Initially it was just one side and then gradually within the next 1 month the other pair of the shoe is also torn.
These sides which are no way in contact with the floor or have any scope of wear and tear, have been torn. Can you explain why? I have mailed reebok 3 days ago, as well but haven't received any response from there end yet.
Since it is under warranty, I either need a replacement or need a full refund of the product; and let me tell you I am highly disappointed with such a reputed brand selling such a product that cannot even last 3 months.
I need quick action on this.