Selfcore.me Signed Me Up for a Paid Subscription Through an Instagram Ad Without My Consent

I am writing about an issue I experienced with a Selfcore.me subscription that I never knowingly accepted and that I am now unable to cancel. On 14 June, while browsing Instagram Discover in the United Kingdom, I saw a Selfcore.me advertisement and clicked on it. Afterwards, I somehow appear to have been signed up, but I did not approve or knowingly confirm any paid subscription. From 15 June, I started trying to cancel this subscription. I looked for a cancellation option in the subscriptions section via the Selfcore.me web page but could not find any clear way to terminate it. Then I tried to contact their support team via Gmail to request cancellation, but my email provider showed the warning “no message was forwarded,” so my message did not go through and I could not reach them. Today, Selfcore.me attempted to withdraw £28.11 from my Monzo Bank account for this subscription. The transaction failed only because my balance was low, but I do not accept this charge and do not want any future payments to be taken. I request that the Selfcore.me subscription be fully cancelled, that my account and card not be charged now or in the future, and that I receive written confirmation that the subscription has been terminated and no further debits will be attempted.