Cancelling Apple Care - "We're unable to verify your bank information. Please try again later"

I have a prepaid Apple care plan on a few devices from AirPods to iPhone.

I have just upgraded to a 17PM and APP3, so I am looking to end these covers before I sell the devices.

My original payment method via Apple Pay is no longer available, so I am opting for funds transfer and have been met with the above message.

Can anyone help? I have tried two bank accounts and IBANs with different banks, and get the same message each time.

The longer this takes to resolve the less money I will get back.