Amazon India — not received refund of return order

Address:

Jamnagar, Gujarat, 361006

I have purchased redmi y2 phone from amazon under my exchange phone. Redmi y2 price is 10999. Exchange ph. Value rs. 3751. After rs. 724 bank discount i have paid rs. 6523. Due to defective piece i returned my phone & refund provided by amazon only rs. 5523 on 27 nov 2018 after adjusting cashback rs. 1000. I called-chat approx 70 times with amazon regarding my partial refund of exchange ph. Value rs. 3751. Every time from 28 nov 2018 given time limit of 24-48 hours but not credited in amazon pay bal. Too much time taking & every time told that ticket raised but no solution given. Excuse given that technical problems, inspection pending, but they are not proceedings my refund. Kindly help for refund my partial refund of my exchange ph. Value rs. 3751.