Select "Accounts, Payments, and Subscriptions" from the following link https://support.roku.com/contactus and verify that you are actually having an issue with Roku. (and not a imposter/scam).
During the setup of Roku, and even after setup, you can always remove your payment method from your Roku account to help prevent unauthorized charges.
Roku Community Streaming Expert
Just another Roku user... I am not a Roku employee.
Insignia RokuTV, Ultra 4660, Premiere+ 3921, Express 4k+ 3941, Streambar 9102