On Purchasing > Invoices you can see the list of all your invoices (click here to see how to find your invoice). Click on the invoice you want to dispute.
On the invoice page, scroll down to the bottom of the page to the “Disputes” box. Enter the reason for disputing (mandatory information) the invoice and click “Raise Dispute”.
The invoice will now be marked as disputed with the reason showing in the “Disputes” box.
To resolve the dispute, enter the reason into the the “Dispute Update” box and tick the “Mark dispute as resolved” box before clicking “Update Disputes”.
The invoice will no longer be marked as disputed.