Unauthorised Debit and Very Bad Customer Service

I had a kwikadvance with Finchoice which was paid in full on 25/04/2018. On 30/04/2018 Finchoice continued to debited an additional amount of R3158.64 from my account - which was completely UNAUTHORISED as I did not give them any instruction to debit my account again and because my kwikadvance was paid up, they have no right to debit my account. I called their customer service the same day 30/04/2018 and spoke to Nokonwaba Demane, who was extremely rude. She said and I quote: "You will just have to wait and call back another day because we are offline." I told her that I there should be something else that could be done to which she responded: "Do you expect me to suck the money from my hand?" I was totally shocked and disgusted with what I heard and asked to speak to a manager. After making me hold for almost 20minutes, I spoke to Yusri Moosa, who ensured me that he will log the refund himself and I can follow up anytime on the progress of my refund. I have called numerous times, left numerous messages for him to call me back, but have not yet heard anything. I cannot spend 30-40minutes a time on the phone waiting for my call to be answered. I do not know why Finchoice feels like they are authorised to debit my bank account for money that is not due to them. This could not possibly be legal and I will look further into possibly logging a complaint with the Ombudsman or taking this further in any way. When I take out a loan, i only authorise you to debit any funds that are due to you and nothing more. That was not part of the contract. I expect someone to contact me back, as I can phone 10 more times, but doubt that Yusri Moosa will be available to take my call. Shockingly bad customer service!