I have purchased one iphone 6 64 gb from paytm and I wanted to buy this same item on 10k cash bach but I was not able to buy because I was logged in.
And same scenario I logged out and was able to see that product with same offer and price.
Paytm is playing smart by having such tools which measures customers trend and attract only to those potential customer.
They will offer good cash backs to only new or potential customers, once you have account amount in wallet then you will not get good deals and you will end up spending un useful to use your wallet.