3 months cancelation for a montlhly conctract?

Went on and signed a free 30 day trial with hope to take on a month to month contract as per discussion with the sales person and manager at the Brackenhurst GymCo only to be offered the contract upfront and told to sign so that if I am interested I need not to do the forms and that their reception will call me tomorrow to finalize everything.when she called I told her im not interested and that they should cancel everything as I dont understand why 3 months to cancel a "month to month "contract .To my disbelief they went on with the conteact and debited my accoubt even with mw saying I withdraw before it even commences.I spoke to a another manager tofay after lodging an online complaint and she says I have to send the 3 month cancellation form for them to cancel meaning they will debit my acc for 3 months frst before they cancel. How is this a monthly contract if I have to wait 3 months to have canceled?