Bata India — Unjustified conditions put by company against compensation of their defective product under warranty

Shoes purchased from Amazon india via online. product was defective under 90 days warranty period. so amazon direct me to complaint directly with Bata India to compensate as the product was under warranty by manufacturer i.e. Bata India. After so much follow up action, they finally agreed to provide me online GV of their online purchase portal after picking up their defective product. Now they are putting extra unjustified condition that I can use this GV only the products which are available on MRP on their online purchase portal. This condition is violation of consumer right to select product as he desires to purchase. Their customer care representative refused to give in writing this unjustified condition stating their policy.