First check: On your Roku, go to Settings > System > About. The email address shown near the top of the screen represents the Roku account to which your Roku is linked. Is this YOUR email address?
If it is not your email address, you are linked to an account under someone else's control. This can happen during initial setup if you somehow reached a scammer's site instead of the real Roku site when linking. Write back for further advice.
If it is your email address, your Roku is linked to your own Roku account, so keep reading.
(If you'd like to set a PIN that must be entered when making purchases on this account, you can do this at https://my.roku.com/pin. Create/Edit your pin, then scroll down and set where it will be required.)
If your Roku is linked to your own Roku account and you are receiving charges claiming to be from Roku that are not represented in either of these pages, contest them with the financial service through which they were charged. They will be able to track the charges back to their actual source.
Roku Streaming Stick +, 3810X, Ser YH0059427035, wifi - Samsung UN55ES6100
Roku Streaming Stick, 3600X, Ser 5S56D8240827, wifi - JVC EM37T
We appreciate you reaching out to us.
For these issues, it may be more effective for you to get help from our billing. Please contact them directly at https://support.roku.com/contactus. Choose the option from the drop-down menu for "Questions about my account or billing," and you'll be able to send an email request there.