Unauthorized debiting for insurance on vehicle

On the 1st of February 2018 Absa Vehicle Finance debited from my account, in addition to my fixed monthly vehicle repayment, and amount of R3907.63 for comprehensive insurance cover for said vehicle because apparently they "never received the confirmation" from me. After talking to a consultant Absa very quickly confirmed that the account was debited in error and they in fact received my confirmation which was sent "Fri, Nov 17, 2017 at 8:34 AM".

They responded in saying that the "amount" will be refunded in 7 days which I find unacceptable, since it took a few minutes to debit from my account. 5 days later only R3553.98 was refunded and after phoning the bank ABSA again they could not tell me why there was a shortfall.

The money in question was wrongfully debited from my account in the first place now I ("the valued customer) have to fight and phone and hold and wait and spend hundreds of Rands on phone calls in order to get MY money back which 14 days later still hasn't been paid. Notwithstanding the fact that I have never missed a payment on this vehicle for almost 3 years since I purchased the vehicle.

I find this kind of thing completely wrong and the banks take advantage of customers and send threatening mails and sms' to their customers, it's shocking, especially since they are in the wrong. Absa has officially lost all credibility in my eyes and the statistics on bank reputations in South Africa has proved that they are not trying to improve on their negative reputation with their customers.