Took full payment but missed delivering items with Rs.300

I ordered several household items from Big Basket. Yesterday, after they delivered I found that 7 items worth Rs. 278 are missing. When I called customer care, they were also misbehaving and told that they will deliver it on Monday evening. So I asked them to refund to my bank account. For that they told that they will not do that. While I was contemplating several options they cut my call and didn’t pick when I called again. So due to undeliverable of items I am facing problems and on top of that they are not refunding it either. Please help me