After the campaign has been paid, your track is sent to the curators based on the selected genres and languages. It's not possible to edit the campaign at this point.
If the mistake occurred while choosing the settings for your campaign or the link to the wrong track was added and you realized it after the campaign had been paid, we can stop your campaign and credit the budget that hasn't been spent yet to your balance. You will be able to use the money for creating a new campaign. Please contact our support team for more information.