KFC — Unable to get refund.

I placed order twice using the coupon and the order got cancelled from KFC side.Third time I ordered without using coupon and they accepted the order.Now I am unable to use coupon with my number.I asked for the refund or promised "chicken zinger" But they denied saying that it is not their fault.But I have screenshots and call recordings regarding this and now I am compelled to go to consumer forum because I feel like the deliberately cancelled my orders so that I couldn't get the coupon benefit this is infringement of my consumer rights.