Nokia India — cash back issue-nokia 7 plus

Hi team,

I purchased nokia 7 plus from your official site on 9 may 2018. At that time, there was an offer going on your site that if you payed by icici credit card or debit card then you are eligible for 10% cash back. The cash back will be credited with 3 months and now it happened more than 4 months and am still chasing your customer support team. I filled multiple times case i'd for requesting cash back but didn't get any satisfactory resolution. My latest case i'd is 495542 and it's was pending since 10 days but didn't get any response. Today they told me that you are not eligible for cash back because payu team didn't capture code at transaction time.

Order no - 6848

Your support team disconnect my call and didn't listen to me. I fed up from your team for chasing my issue.

Who is responsible for this and what is my fault for not getting cash back.