Tandem Automatically Renewed My Subscription Without My Permission

My annual membership on the Tandem app, which I had originally started voluntarily, was automatically renewed just moments ago without my permission, even though I did not want to renew it. The membership fee was charged directly to my credit card. I did not receive any clear or understandable notification about the renewal, so I do not approve of this automatic charge.

I request the immediate cancellation of this renewed membership period and a full refund of the amount charged to my credit card. I kindly ask that this transaction be reviewed as soon as possible and that I receive a prompt response regarding the issue.