Cashback Not Given for Sale on LeTv Le 1S on 9 Feb 2016 by FlipKart !!

This is to inform and complaint about my purchase of mobile LeTv Le 1S on 9 Feb 2016 under an sale .As per the condition of the sale – if any customer buy LeTv Le 1S on 9th Feb 2016 using the Axis bank debit/credit card - would be eligible for additional 10% of cash back; that will be credited in April 2016 by date 10th.
I had participated in the sale along with my office collogues to purchase the mobile on 9th Feb and used the Axis bank debit card to make the payment for the mobile and order number was - OD105185488467086000.
And one of my collogue - Gurpreet Sing Nagi also purchased the same mobile using the AXIS bank debit card at same time with Order number - OD405185661275441000.
On 22nd of March - he got amount credited Rs. 1099 on behalf of the cash back for the sale of mobile - LeTv Le 1S.
On 14th April 2016 – I had contacted the Flipkart customer care (Reference number - IN-1604141822380575068). At first – he denied that there was not any such sale and after giving the reference for Gurpreet’s order Id – then he confirmed that there was a sale.
However they inform me that I was not eligible for the sale/cashback so no amount transferred.
It is really embarrassing that if in the same date sale under same condition (fulfilling all terms as per the sale) two customers purchased the same thing then – how would one eligible for cash back another person not ?
I have also checked on the Flipkart portal and nowhere mentioned that net banking with AXIS bank debit card was not allowed and not come under cash back. If I had ever aware about that there is no cash back for this sale on such constraints; I would had canceled my purchase. As per the condition Customer had to use the either debit or credit card of Axis Bank for the transaction & what I had done. If my transaction was with another bank – then definitely I would not eligible for the 10% cash back.
I had you even called the Customer Care to change the delivery person’s name from Manoj to me and that point of time - I had confirmed with the person also whether I am eligible for 10% cash back or not - after the confirmation of the person I had carry on with my purchase otherwise I would had canceled the deal.
I have also checked on the Flipkart site and in my invoice as well; I have not found anything mentioned like that Customer should not purchase using the net banking. Eventually - using the net banking also used my AXIS debit card account for transaction. If there was any such different than it should be mentioned in the term and condition. I had to raid it very carefully and even some of my colleague opted this option.
Another aspect - This is your moral obligation that to report to the customer that customer opted the wrong option and not eligible to the cashback even though sale /transaction done with offered bank. Customer could eligible for offer by just selecting another radio button and using the same bank.
They had not putted any note on the invoice whether customer eligible for cash back offer or not – IT IS NOT THERE. If I was aware that just choosing a different option like choosing Net banking instead of debit card option make such difference – I would definitely cancelled the deal & would take the offer another time.
During the sale I had called the customer care & Customer care executive confirmed that I was eligible for 10% cashback at the time when I called to change the delivery receiver’s name. If it was the case then person should inform me and definitely I would had cancelled the deal. I could had purchased the mobile either in next transaction or next sale.
This is the mistake & miscommunication from Flipkart side, then why should I only suffer?

Please help.