Swiggy - Item missing in the order

This is regarding order #************.. I ordered four items but got only three items delivered. Mutton Biryani was missing from my order. When i tried to call the restaurant they are not attending the call.

I have contacted the customer support and they asked me to send an email ,which i did asking them Either to ask the restaurant to send the missing item or initiate the refund but the response i got was very silly(automated response) as if they are gifting the food to the customers . It's my hard earned money .Why should I pay for the item which i didn't receive?
I wanted to raise a complaint against swiggy as there are so many customers like me being looted by them everyday.