On the Zebb platform, we (Zebpay) are not the counter-party to your trade. This means that we do not sell you cryptocurrency or buy the cryptocurrency from you. All the platform does is make the entire process of buying and selling between individuals as simple as possible.
Therefore, at the time of taking your order, the platform can only show you what was the most recent rate at which a successful transaction occurred. Once your order is placed, the price may have increased or decreased. This is reflected in the price difference between displayed rate and order confirmation rate.
For more information on how the transaction works, please refer to the article on Instant Buy/ Sell.