Is it actually coming from Roku. There are many scammers that hide things behind fake names. You can try contacting your bank or credit card company and see if they have more detailed information. Even online, you may be able to click on an entry or something to get more detailed information.
Are you paying for Netflix, etc through Roku, or directly? Yet another reason to never subscribe through Roku, as that way you know who is charging. If you have no subscriptions through Roku, you can go to your account on the Roku website and REMOVE any credit/debit card linked.