Mantri Square Mall — I'm complaining about irresponsibility of the saler

Address:

Mantri square mall, Bangalore, Karnataka, 560003

I have taken Samsung A30 on 11/08/2019 in relence digital mantri square mall, Bengaluru the salesperson told that there will be no cost EMI and cashback of 10%. But I have got nothing in additional to that I have been charged 13% interest. When I gone there and asked they haven't properly responded. They told that there is no Cash back but HDFC credit cash has these offers. If there is no cash back mean why to lie to the customer. Please clarity and resolve this