My Duolingo Membership Renewed Without Authorization

I purchased a paid Duolingo membership a year ago, but this year it was automatically renewed without my consent, despite not having an active auto-renewal instruction. I do not wish to continue the membership and would like a full refund of the charge. I'm also confused as to how the renewal happened when the automatic payment option was turned off. I would appreciate assistance in resolving this matter and getting my refund processed. Thank you!