Swiggy - Didn t receive order and swiggy has refused to pay refund as well

I ordered on Swiggy Instamart on *th Aug with order id #*************** and total bill of Rs ****.
After some time of ordering when I checked the app, it showed my order as cancelled.
When I inquired on their chat support, they told that my order has been cancelled with ***% cancellation charges because you have not received the calls of our delivery agent.
But first neither their delivery boy reached our home and not did I receive any calls from them. I showed them my call logs as a proof and demanded that they should show their proofs as well of calling me and not receiving by me. But they are not showing any proof and repeatedly telling that there will be ***% cancellation fees.
I contacted them on their email and getting the same answer.
If the order is not cancelled by me and the delivery boy has submitted the order back to the warehouse, so how can swiggy impose ***% cancellation charges. I do not get this.
I want my refund back, I am a student and lives in PG on a tight budget. I have ordered groceries as my monthly ration and they did this. Shame on Swiggy. I will never order gain from them unless I receive my refund.