2GUD BY FLIPKART - Not providing refund

I had return my Asus zenfone *z for warranty claim as it was undergoing some issues. They told me that we will contact you after ** working days but no one showed up. Then I called them after ** working days they told me to wait for * more days. After * days the told me that we are unable to repair your device so we will provide refund/replacement. But its almost a month now they are not giving any refund and just extending the date every time I called them. They have worst costumer support and back end team.