Amazon India — after 50 days not give refund amount.

Sir, i was book at 13 july 2017 one plus two stanstone black mobile phone ₹16.590 by amazon order number#[protected]. When i received it and used i found it's battery working not good than i complaint on amazon customer services on 27 july 2017. Customer care suggest for replace and refund. Than i sent mobile phone by return amazon address by indian post at 14 august 2017and delivered status show in indian post tracking information 22/08/17 and amazon accept it and mail me for refund at 24 hours but now i got no refund. So please kindly request to refund my amount.