Un authorized debit order

I was approached by fnb consultant for the group funeral scheme. I gave them the date to deduct, later I realized that the date I gave them is not suitable for me. I send them email not to deduct money from my account. Come monthend they deducted from my account. I called them to cancel the policy if they feel that I must pay even if my finances are not in order yet. They managed to close the account but they don’t want to refund me. I want my money back because I send them email not to deduct from my account.