Discovery stole 6 months of premiums

Discovery is still subtracting premiums 6 months after I canceled. I gave Discovery the mandatory 1 month notice and emailed it to the address that the online consultant gave me. I got a response to my email, asking to confirm my cancellation. No extra details were given. I responded affirmative to the email.

I lost access to my bank account due to immigration and my phone not being in South Africa anymore. I discovered that they have subtracted 6 months premiums from my bank account (after the 1 month grace period).

They are refusing to refund me.