Lenovo — Purchase Issue

I have purchase a laptop during Independence day offer period on Aug 11. During the offer period i got that confirmation, if i use HDFC bank credit card for payment - Rs. 5000 min (10% of bill amount) cash back.

But i never got my cash bash amout from Lenovo.
My purchase order number: [protected]
Product ID : 81Y400BSIN
mobile Number: [protected]

I tried multiple times reaching out to customer care, sales department, post sales department over email & their customer care numbers,
But i never got any proper respose back from Lenovo.
Infact customer care raised couple of complaints or tickets inthier interal systems.

But i never got the cash back offers.
Lenovo cheated me during the purchase (ever i got the confirmation over the call & chat also for the same from Support Engg. That i will surely get my cash back.)