Takes any amount they want on home loans.

Standard bank home loans takes any amount they want every month, without notifying customers of the increase.They say it's because the number of days in the month are different and that's what calculates the rate, but then why in Feb when there are less days does it still increase?? Why has the amount never decreased only ever increased? I called, 25mins on the line and the agent couldn't even tell me why. Then she said she'd find out and call me back. That was the 19th Jan. And still no call. In Feb I was told interest rate increased and given an amount (notified by letter) and then the debit order takes more than the amount I was notified of! I know your system is broken and I think you are *****ing money from us without us knowing it! There is absolutely no customer service from them! Can someone call me from the loan department!