Discovery Vitality is a big *******

Discovery was quick to sign me up for the vitality programme giving me a free membership for 3 months and they started deducting without even a notice. Now all of sudden when I want to cancel I am given the run around telling me I need to contact HR, they never needed me to contact HR to consent when they decided they wanted to deduct the membership fee and now that I want to cancel I must all of a sudden contact HR.