Student loan *******

I app**** for a student loan at standard bank and it was gladly approved and immediately when i started working even though it was part time I started paying the loan off monthly...all of a sudden standard bank feels they have the right to take out lump sum of money out of my account with out my authority what's so ever this is unacceptable if standard bank had told me that signing the student loan agreement ment that they will be taking my whole salary and saving anytime they feel like it with out consulting me then I wouldn't have even bothered...they depriving me of everything I worked so hard for...I planned to renovate my mother's house with my first salary but now I have to disappoint because standard bank does as they please in my account and this would be understandable if I wasn't paying my student loan off...but I am every month I pay a certain amount to my loan I need my money back,money that I've worked hard for and please train your loans department calls centre on customer service they have no idea how to speak to clients your response is highly anticipated and over dued