Only you can cancel the subscription you signed up to
Other members cannot do it for you
It is not a (scam, I assume you mean?)
You did give them permission/consent when you thought you were going to get a free voucher
Did you read the thing you ticked you read?
Nope
You signed up to get the voucher, and in doing so and giving your bank/card details agreed to the monthly fee
Don't tick you have read and agreed to things you have not read
AND give over your personal details, including bank details
Next time it might really be an actual scam
