Insurance *****

Absa activated a policy with my consent of debiting my account but because they have my banking details, they just activated the policy, Now when i ask they to cancel the policy the telling me that i must provide a singed cancellation letter and attach certified ID copy. The cancellation letter which i don't even know where to get it and i did even receive any policy document but every month, they trying to debit my account for that insurance. Now they don't even reply on my email when i ask them where to get the cancellation letter which i need to sign and i sent my certified ID copy asked them to cancel the policy, still no reply and they also tried to debit my account this month. Where can i report this?