Amazon India — no credit of 1000 rupees cashback against order #[protected]

I purchased one ifb washing machine from amazon india under the promotion offer of 1000 rupees cash when purchase is done with any prepaid mode. To fulfill this condition i ordered using credit card. When product was delivered and installed but cashback was still not credited. After that i raised this issue with amazon customer service team umpteen time but to no avail. 3 times they asked to wait for 7 working days hence spent almost one month in this process yet no resolution done.
Now i am compelled raise this issue in this forum to get the refund of 1000 rupees cash.

Please do the needful