Unauthorised/Cancelled Debit Order Mandate

They called me and sold me a DSTV Streama, I informed the sales agent that I did not have a DSTV subscription, she said that I did not need one. I received the device but when I attempted to connect it, low and behold, it needed for me to have a subscription so I called them and requested a cancellation of the order as it was whithin 5 days. They said that they needed to conduct an investigation first to establish that the agent misrepresented the product, which they did and it was confirmed via the recording that the agent **** to me. They subsequently collected the device and proceeded to debit my bank account, I have emailed and called them on numerous occassions to cancel the Debicheck mandate, I suspended the mandate on my FNB account but the debit order still went through...WHY ARE THEY DEBITING MY ACCOUNT?