Amazon India — refund has not been initiated by them

Address:

BH-2 , Room No. 171 , Birla Institute of Technology , Patna ,Near Patna Airport, near Patna Airport and besides Vetnary College, ph no. 9102971284, Patna, Bihar, 800014

Sir/maam
i have purchased a boat bass 225 earphone of around 570 rs ..i found is defective and returned it on 17th jan 2019 but this now the money have not be refunded to me, when ever i call them they say an investigation is going on the product as the recieved one is not the boat bass 225 headphone ...i have received a msg of retun picked up and i have mailed the too but no response from there side ..