Do you have HBO Max? That might explain the "Roku for Warner..." charge. You can see what you've subscribed to through Roku by logging into https://my.roku.com using the email address that's displayed on your Roku device under Settings->System->About. Also, do you have multiple Roku devices? If so, you might have multiple Roku accounts. Check the email address displayed under Settings->System->About on each device.
For billing support, you have to start at https://support.roku.com/contactus. You should be able to get to options to communicate with a human, but it's probably best to try during business hours Pacific time.
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