Adding a dispute, and muting an invoice are done by a very similar process.
Select Accounts from the left menu
Find the relevant debtor (you can search for them, or scroll through the debtors)
Click the empty space by the debtor to see the invoices drop down
Select the invoice(s) that is disputed
Click the three dots to see the drop down menu
Click add dispute (or mute invoice)
You will then be prompted to add a description of why you taking this action;
Add as much relevant detail as you can.
Decide if you require a response about the dispute then
Click confirm.
Once the dispute, or mute is added to an invoice it will be shown in the contact history and in the invoice view
NB:
Future email reminders will take the disputes and mutes into consideration when displaying their account summary.
Muted invoices will be excluded from the email, and
Disputed invoices will show as (disputed)