Adidas - Inferior quality

I had bought a Adidas cap of Rs **** at Mumbai Phoenix mall. However, the cap was of inferior quality as the cap got discolored and there was a strange stain coming from inside which was not going away after cleaning.
I raised the complaint to Adidas grievance officer so many times. They have written to me saying my warranty is over. I live in North east of India and it is not possible for me to travel to cities very often. I have given my reason for the delay. However, I have complained about the quality which they refuse to accept and sort my problem. I have asked them to either replace or refund. They are refusing now.