ABSA debits my account without consent

I find it very disrespectful towards me as a customer, for a bank who has access to my account to just feel free to debit my vehicle account WITHOUT my consent. NOT even a phone call,email or letter to advise me of their intentions. What makes Absa think they can just go ahead and scratch in my account. They have no idea what my budget is like and what I needed that money for. Do they feel that because they are a big bank, that they have every right over their customers. They have left a better taste, and i will not advise anyone to take out an account with them.