Refusing my Refund due to a mistake

I signed up on a free beauty Course with shaw academy when i was online a pop up came on my screen and i accidently clicked on it and my bank account was debited TWICE and now they are refusing to refund me after i emailed their billing department and spoke to a agent, telling them i am no longer interested. i am very unhappy with this and this is the reason i will not reffer their institute to anyone i know

499 rand was deducted twice from my account