Swiggy - Missing items in order

On *th March, I ordered on Swiggy (from kfc), but in the order items are missing.
I raised a help thread and bot asked me to choose between replacement or refund for missing items.
So, I opted for a replacement order. But the replacement order got so delayed that finally it was cancelled from swiggy end.
While cancelling the replacement order, I asked for refund. But the executive said that they are seeing Rs.* paid and it is a COD order and I can't receive any refund on that order.
I clarified that it was replacement for a missing item and hence I am eligible to receive refund. Then she asked for bank details and said it will be credited in *-* days. But it is not credited.
I wrote back to swiggy. After many mails they said that they will refund Rs.***.
But the missing items are worth Rs.***
(total order is Rs.***) and also If I have had opted for refund in first step, they were about to refund Rs.***..
I wrote back several times saying that refund is less than the worth of item. But they are adamant on refunding only Rs.***

Original order ID-************
Repeated order ID-************