A fix was implemented on Sunday, January 26th, at 12:53 UTC. We are actively monitoring the situation.
Posted Jan 26, 2020 - 13:01 UTC
From 12:27 UTC on Sunday, January 26th, the premium billing system is experiencing an irregularity that may prevent you from viewing invoices, adding or editing payment method, or from upgrading or downgrading service. The issue has been identified and a fix is being implemented.