Shaw Academy - Unauthorised Debit Order

I saw an adverti*****t last year November 2020 regarding a free course for a month, and that I would not be subscribed to anything as it was just 1 month trial. Unfortunately I realised I would not have time to do the free trial and I cancelled without even starting the course, to my disappointment I started receiving emails about failed subscription payment. My main problem is now my account has all this charges for failed debit orders and I am now owing over R300 to my bank because of unauthorised Debit Order From Shaw Academy! I have sent emails and try to call but no response. I want Shaw academy to cancel the unauthorised Debit and settle all the fees accumulated in my account!