In the event that you need to update the payment method associated to your Stamps.com shipping provider account, you have a couple of options available to you.
1. This Stamps.com article will guide you through updating your payment method by either logging into your Stamps.com account online or by updating the payment method through the Stamps.com software.
2. If you need further assistance you can reach out to Stamps.com customer support directly. Their awesome support team will be more than happy to assist you.