If you have an overdue payment, you'll see this error message displayed as a banner, and you'll be unable to book shipments:
Overdue payment – Update your billing here to continue shipping
To continue shipping you'll need to pay the overdue payment, which can be done here. Or by going to your billing section in Shiptheory and clicking Manage Payment Methods


If you encounter any issues, please feel free to contact our support team. You can call us on 0117 403 4313 (UK) / +1 (629) 666-6726 (US) or reach us online here.