Create an invoice for a customer for a specific type of merchant bill
createInvoice( responseBack, invoiceConfigurationId, ref, amount, date )
| Name | Type | Description |
| responseBack | Indicates which function to be called when a response is received. | |
| invoiceConfigurationId | The id of an invoice configuration for a customer | |
| ref | The reference number of an invoice | |
| amount | The amount of money to pay in cents | |
| date |