By accessing the work area you can download at any time the invoices related to the Professional Account and the services of SiteCo.
Click on the Manage Site on the right to access to the panel Domain Profile.
From the Domain Profile, click on Historical Bills to see the full list of invoices.
From Billing Data, you can edit the billing information of your account: click on Save to confirm the changes. The changes will be effective from the next invoice issued.
To know: if you are unable to download the invoice by clicking the download button, it is very likely that you have enable an extension on your browser that blocks the download. Disable browser extensions, and try again to download.