Standard bank deducts money without signature

After receiving a sms earlier this year I had to send insurance confirmations to standard bank foe my car. Which i did. 3 days ago I recieved a sms from them again to inform me that they have added me to hollard insurance and that this will be deducted with my monthly premium. I immediately phoned them and advised them that i did send through the docs and that i did not authorize them to deduct any other insurance. Yet they went through with this after i again sent my proof. Working in the financial industry i am appauled by their lack of customer service.