How do I get rid of Roku charges?

Hello there, I'm wondering if you could help me out with a problem I'm having. I've been noticing some charges from Roku on my bank statement and I'm not sure how they're getting there. I don't have a Roku account and I haven't subscribed to any of their services. Could you please guide me on how to get rid of these charges and make sure they don't appear again in the future? Thank you in advance for your help.