Amazon .in - Refused to give cashback after commitment

I had purchased two tyres separately and I was supposed to get cashback for *** on each.
I dont understand their conditions so i called Amazon customer care to confirm whether am I elegible for both. They confimed yes.
Then i called them again that i had received for only one and second cashback has not received. They told me it took three days and today is last day and if you will not get it by today then tomorrow we will do it manually.
Next day after order delivered and call them again and at that time they refused and told me that it is only for one and told me that Amazon people has given false commitment.
In this case why should I suffer? It means they can give any type of false commitment on behalf of Amazon and after that they can refused? This is very wrong. It is a clear case of cheating.
Order date - ** Oct ****
Order Number - ***-*******-******* and ***-*******-*******.
I have recordings with me which happened with Amazon to validate what i am saying is correct.