How to change an invoice submitted in error

Go to the Customer Zone and click 'Sent Items' to see the invoice you have sent.

If the status is With Customer, then the invoice has already been delivered to the customer, so it cannot be modified. In such cases you need to send an email to your customer asking them to cancel it. You will then need to enter a new invoice with the correct details. As you cannot re-use the invoice number, you could add a code to make it unique (e.g. if the original invoice was '12345' you could call this one '12345a')

You can only actually edit an invoice if it has been quarantined. The option is available on the quarantine list.