Reliance Trends — about exchange of shirt

Address:

New scheme road,pollachi, Coimbatore, Tamil Nadu, 642002

I got basics blue shirt, but i have the same colour, i got it throw voucher, so next day i gone for exchange but the staff told that they they won't exchange the product brought in offer, i request them to change the colour of the product, but they refuse and told can't able to change. Kindly help me to change the same brand basic shirt only the colour of the shirt for this one time, we have purchase for nearly 3000 for family and friends