Flipkart — Items delivered as Cash on delivered without ordering

On last Sunday I received some items as cash on delivery. The delivery person did not show the items without cash. After getting the cash the person went away. When I opened the package I was shocked to see the item I received which I or my family never ordered. Later while lodging complaint with Flipkart it came to know that some unknown person whose name I never heard in my life has ordered this from his account as Cash on delivery. Now the Flipkart neither accepting this item as return nor refunding the cash amount. The Flipkart helpline team refused to accept any request. Now I am at loss without any fault of mine.