Did you recently sign up for a free trial to HBO? Please be aware that if you previously had a free trial through the same Roku account (on any Roku device linked to your account), you will not be eligible for another free trial with that specific service. We highly recommend reviewing the terms for any trial, prior to signing up.
We would recommend logging into your Roku account online at my.roku.com and clicking Manage your subscriptions to see if you signed up for a HBO subscription.
For further assistance with billing related issues, please reach out to our support team directly here for your 'Account or billing' issue, here: https://support.roku.com/contactus. They will be able to further assist you.