Technology to make a smartphone with these kind of specs for such a low price doesn't even exist.There should be something mysterious about this.We should understand the fact that no any business entrprise can exist without making profit.How can they make profit if they sell this phone for just Rs 251? Therefore I'm 100% sure that there is something wrong with this phone.
He has paid through Paytm wallet,I have also paid the same way as it is much more secure to pay through it rather than directly using your debit or credit card,but u can also use debit card/Credit Card/Net Banking