Massage Envy Membership for a massge parlor that is impossible to get out of without a doctor's note Oklahoma City Oklahoma

I bought a 12 month membership to Massge Envy.  The benefits were supposed to be that members receive priority over non-members and therefore do not have to book a massage weeks in advance.  I was told that members don't have to wait, and that a therapist should be available to me within an hour. However, whenever I call--even 3 or 4 hours in advance--they usually say that they don't have any therapists available.  Additionally, the employees who take phone calls are very rude.  I do not like their service and do not find the membership to be worth the money.  However, they will not allow me to cancel my membership without a not from my personal physician saying that I no longer require their services.  I do not receive Massage Envy's services for medicinal reasons. I was not sent to Massage Envy by my doctor's recommendation.  If this were a legitimate medical establishment, my health insurance would cover the cost.  I have found out that Massage Envy does terrible business and makes it impossible for members to cancel their memberships.  Why can I cancel a prescription from my pharmacist without a physician's note, but I can't cancel a membership to Massage Envy?