Refusal to assist after being debited incorrectly due to "system error"

After my vehicle was written off it took Westbank two weeks after receiving all the necessary information from my insurers to action the settlement and shortfall. I then phoned them in this time to make sure that I would not be debited going forward. I dealt with a Prudance and Pretty Dhlamini from Westbank who assured me that I would no longer be debted. Of course on the 2nd of the new month I was debited and phoned to find out why. I was told it was a system error, so I ask for them to reverse it, they said I need to ask my bank FNB. FNB said they could not reverse the debit and that Westbank need to reverse it. Westbank refuse to do so and say they cannot reverse it. Bottom line they are pathetically slow and couldn't care less or even bother to try and help.