The administration and maintenance of Microsoft Exchange Server to ensure secure, reliable, and efficient email and collaboration services across an organization.
Generally speaking, you should follow the instructions here: https://learn.microsoft.com/en-us/microsoft-365/commerce/billing-and-payments/manage-payment-methods?view=o365-worldwide#add-a-payment-method
In case the process is not working for you, best contact billing support: https://learn.microsoft.com/en-us/microsoft-365/admin/get-help-support?view=o365-worldwide