Kohinoor Televideo — cash back issue

Address:

B 502, RITU PARADISE PHASE 2, NEAR GCC CLUB, HATKESH, MIRA ROAD EAST, Thane, Maharashtra, 401107

I had purchase a samsung fridge on 25/10/2019 from kohinoor (Mira bhayendar) at rs 41000. I was informed that i well get a cashback of 20% (10% from samsung and 10% from hdfc) after 90 days.
When i visited that outlet on 8th march 2020 (After i haven't received cashback), they are saying that cashback is on emi and nobody take responsibility of my loss of 20%.
Certain things to highlight:
1) i wanted to purchase on emi but the salesperson and cashier debited the whole amount and convince me that the amount is blocked only. And nobody has said the whole amount is debited and i will not get a cashback.

2) when i went after i got the statement in november, very carelessly the staff said i have to checked it that it was on emi or paid in full. But its not their responsibility.

This incident has already downgraded the image of kohinoor and seems that after getting the amount nobody is there to help the customer. Its seems that kohinoor staff has only aim to sell their product by hook or crook. And there is no place to solve the customer issue.
Attached the invoice copy.
Looking forward to help me out.