I ordered an MI powerbank from paytm, and I ran few tests on it given on MI forum for genuineness(link to forum:http://en.miui.com/thread-18452-1-1.html).
And I found that the product I got was a fake one. I emailed paytm regarding this and they are not replying to my emails. Also, the phone number of the retailer given on the invoice is not valid.