Not refunding the money for a wrong product sent to me.

I bought a mosquito net (foldable). they sent me a wrong product (a substandard, green piece of net material with threads). They took the product back and promised to refund the money. Till date, I have not received the refund in my bank Account. Order Date: 22 Apr 2015. No resolution till date. The customer support team is telling me that they have refunded the amount. But, they are not providing any transfer details / reference number. Its June now, and the matter is still not resolved.