Hello Kevin Payne,
As pointed out by Mahesh, you can raise a support request completely free here:
https://azure.microsoft.com/en-us/support/create-ticket
Azure Billing and Subscription support is offered by Microsoft by no cost and it's for free.
Just pick issue type subscription management.
These tickets are handled by humans and it will be attended to
In the meantime before you create the ticket you can try removing all the resources to avoid any charge.
Then try again
After you cancel, billing is stopped immediately. However, it can take up to 10 minutes for the cancellation to show in the portal.
You can mark it 'Accept Answer' and 'Upvote' if this helped you
Regards,
Abiola