Extremely poor business ethics

I signed up for the 4 week free trial to see what it's all about and after completing the first 30min module my screen was bombarded with pop-up messages. One message in particular that I accidentally clicked on automatically took R499.99 out of my account without asking me to confirm my purchase or even letting me know that I will be paying money. I very quickly cancelled my trial (after just 30min of having it). I then got around 10 calls from different sales agents asking me to explain why I cancelled and kept trying to convince me to keep my account.

I then realised that the R499.99 that was taken from my account was for the certificate that I would receive at the end of the full course (including all modules, quizzes, and assignments). But I have cancelled my free trial so I will not be receiving any certificate. I sent an email to *** kindly requesting a refund and explaining the situation. I then got a response saying that no refund will be issued because I purchased an "add-on". Even though I do not and cannot receive this add on..

The lady also informed me that if I proceed to delete my account with them, they "can no longer able to assist with any further queries once deleted". But if I do not delete the account, they will start billing me monthly once the free trial ends.