Flipkart — Account block after requesting refund

Website: Flipkart

Flipkart delivered me a different of same product and also the delivered product was already a used one by someone & old. I had requested a refund 4 times but they cancelled it everytime by saying that delivery boy confirmed that the product was intact.
After requesting refund for the 5th times they just block my account. I need proper investigation and want refund.