PhonePe — I didn't get cashback from phonepe.

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PhonePe Mobile Application

There was a offer on Coolwinks.com that if you purchase a eyeglasses using Phonepe payment gateway within 25 Dec 2018 then you will get Rs.1600 cashback.
So I purchase a Eyeglasses from Coolwinks.For that I used new Coolwinks account, new Phonepe account which is configured on new mobile handset. But still I didn't get any cashback from PhonePe.
So I called customer care of Phonepe, firstly they informed me that, it's a technical issue so we are forwarding this issue to Technical dept and you need to wait till 27.12.2018. So on 27.12.2018 I called Customer Care once again they informed that you can't get cashback because you already took the benefit of this offer. But the reality is that as I informed you above, for this offer I opened a new PhonePe account and configured it on my new phone. so there is no question of taking benefit of this offer. So here I want to mention that Phonepe is clearly chatting me by giving such a silly answer.
I also wrote mail to PhonePe but they gave me the same reason.