Amazon India — cash back not received, sbi debit card used to purchase lenovo z2 plus

I had purchased lenova z2 plus mobile. Order #[protected], order date 10 aug 2017. I used sbi debit purchased lenova z2 plus mobile. Order #[protected], order date 10 aug 2017. I used sbi debit card for purchase, but cash back not yet received for purchase, but cash back not yet received. When will i get my cash back amount. Kindly let me know as soon as possible.