Thanks for reaching out to the Roku community!
We appreciate your patience regarding this matter. I understand that the Roku account linked on your Roku device is not your email address and you have linked your payment method to the Roku account on your device.
We would recommend reaching out to our Billing- account team to see what further assistance they can offer, please contact them directly at https://support.roku.com/contactus. Otherwise, you may need to contact your card provider to stop any recurring charges on your card moving forward.