Nedbank un-authorise debit order

I’ve been to Witbank Nedbank Branch on several occasions regarding an bank deduction on my account. I did not authorize this debit order. At the desk I’m told to do it on the phone, where promises of cancellation and payback is made (and requested to wait for a few weeks). When I return after 4-6 weeks nobody know anything and the whole process starts again.

Back to the branch my request was escalated to Head Office. Again promises to stop the deduction was made but the amount when from my account again. For the payback I’m requested by H/O to go back to the branch as they are the only one that can do this. At the branch they say I have to take it up with the Call Centre. This deduction is been going on for +/- 2 years (an amount way over R4000 and counting). I've been to the bank countless times. This deduction is a NKB debit order that is made by Nedbank for an internet service, and they cannot stop this themselves?