Big Bazaar / Futurebazaar / Future Retail / Hometown — cheating by big bazaar kalkaji metro station and future pay giving fake offers of cashbacks

I purchased the following items from big bazaar kalkaji metro station under the offers scheme valid from 28 sep to oct 2, but didn't get the cashbacks as per the offers.
1.2.25 litre frooti bottle at the offer price of rs 70 and future pay price of rs 44 (Rs 26 cashback). I didn't get the rs 26 cashback
As per the offer. Tax invoice number is: [protected] date of purchase 28 sep 19.
2. 700 g kissan mixed fruit jam bottle at the offer price of rs 165 and future pay price of rs 132 (Rs 33 cashback). No cashback was given to me.
Tax invoice number:[protected]. Dop 30 sep 19.
I have contacted future pay and big bazaar customer care units a number of times and sent them emails giving proof of the bills copies and the offers. They are not acting in the matter and trying to be very smart by making excuses like their servers are having technical issues, wait for 2 to 3 days and sometimes not responding at all. They all are crooks.