If the payment of your invoice failed, all you need to do is connect to your Twenga Solutions interface, and click on the roll-out menu on the top right of your interface, just next to the name of your site, then on "Invoices":

On the displayed page, you will be able to find all of your invoices, paid or waiting to be paid. It's by clicking on the button "Pay" that you will be able to manually pay your invoice:

Warning, your campaign will be suspended if the payment has not been paid within 48 hours.