What if the customer underpays or overpays the amount ?

If the amount paid by the customer differs from the amount displayed on the hosted payment page, the merchant will receive an email notification indicating whether the payment was over or under the expected amount. Any follow-up actions will be handled manually—if it’s an overpayment, the merchant must process a refund using the standard refund process; if it’s an underpayment, the merchant will need to request the customer to pay the remaining balance.