Iq Boost's Unexpected €39.90 Monthly Fee Without Consent

I purchased a one-time IQ test from the website IQBoost for €0.50. Immediately after, without my knowledge or consent, an additional €39.90 monthly subscription fee was charged to my card. I only intended to use the service once and never requested any membership. As soon as I realized, I contacted my bank, filed a dispute, and cancelled my card. I demand the immediate cancellation of this unauthorized subscription and a full refund of the €39.90.