Flipkart - No refund after pick up

I ordered one set of shoes but size got a title big, so i return it immediately for refund. They pickup it ** October ****, next day they cancelled the refund i called the customer service they told to i will get my refund before ** October, didn't got so i called again they again told me i will get my refund within * November, didn't got. I again called the * November they told me that i am not getting the refund because they can't track product the product and they are looking in it. Next day they called me and told they they can't give the refund because the product got lost and they can't do anything about it.