Order can be canceled till the same is in under processing. You would see an option to raise issue within 'Transaction Details' section under the main menu of your Portal then select the transaction you want to cancel. A transaction cannot be cancelled after the successful proccessing of the service.
In case of failure of transaction by payment gateway, the refund will be provided against that transaction in your source payment method. After the refund has been initiated, as per the Refund Policy, the refund amount is expected to reflect in the your account with in 5-7 Business Days.