1. Login to your account (top right-hand corner)
2. Click the Invoices tab
3. Find the invoice you wish to pay & click the View Invoice button
4. When the invoice is displayed; a message will appear stating the available credit on your account.
You can nominate the amount of credit you wish to apply to the invoice & click Apply Credit.
The credit will be applied to the invoice - if paid in full, the invoice status will change to PAID.