Swiggy — misleading bills

I had placed an order which amounted to inr 400 however i had a coupon which i was entitled to redeem for order inr 299 and above but unfortunately even after ordering food for inr 400 i did not get the discount and on top of that the customer care were least bothered to resolve the dispute and kept me waiting with the hope that my money would be refunded. Also the approach of the customer care was not cordial and he was utterly unprofessional. This is not how a customer care personnel should be behaving with its customers. I was also promised for a call back fro the customer care too help me out, but that turned out to be false too.