Bugs and Feedback channel on discord isn’t customer service anyway, and neither discord nor an in game petition is going to be able to help with billing issues regardless of whether they got back to you (others have reported getting responses to petitions after the backlog a few weeks ago, for whatever it’s worth.
If you haven’t already, make sure to contact them through https://www.funcom.com/help and not a petition. And even if you have and have not gotten a response, try it again (though if I remember right they use zendesk, and you should get an automatic email in response when you use that form. If so, it should contain a link to your ticket so you can view the status. But I could definitely be mixing them up with other companies).
But again, petition will most likely not be able to help with this (though you can ALSO view the current status of your petition and add notes to it).