Cancellation of Vitality

I recently joined Discover Medical aid. I received a call offering me a free 3 month Vitality benefit. I was advised to cancel it after 3 months if I no longer need it. I signed up in April nd cancelled in may via email to the Email address *** Vitality -MailRef#***# . Only to find out that my Vitality is still active. The only response I received from my cancellation request was an email requesting for a cancellation date, but there was no follow up after that email. Kindy provide me with proof that the first 3 months where the 3 month promotion which I was not supposed to be billed for, and a statement showing when Vitality started billing and please back date the cancellation request to the month of May.