Non Return of default item by the Paytm

I online purchased Ambrane 1000 Star Power Bank 10400 mAh from Paytm against order no. 1020341925. Paytm has sent me default Power Bank. I lodged complaint in Paytm for return/replace the item. Paytm has not returned/replaced the above item without any reason even after passing of more than 10 days of my complaint for return/replace the item.