FNB penalises you for having savings

I am livid with FNB and their bad faith coupled with nothing but excusesfrom their staff. I have a home loan with FNB, the terms of which I honour religiously by monthly debit order. I decided to take their advice and choose their flexi option for the home loan. I put my savings in the bond. Low and behold come the end of the month FNB debits me twice and their call centre agents tell me I can only access my savings on after 5 working days (effectively a week, barring any public holidays). What I was told when I took the home loan was that I could access the savings at anytime. What they never told me was that they would penalise me for having savings by denying me access to the equivalenvt of my debit order for th minimun of a week every month. I told my banker about this problem and she said they were investigating. What is there to investigate if this is what they do all the time. I feel like I am being made a fool of and FNB is being dishonest. Why is it my fault that they take a week to clear the debit even though I bank with hem? What happens the day I need that money for an emergency and they are still processing their own issues. I pay what I owe.....why punish me with an effective double debit? And why did you not tell me that I would be debited twice because I have savings but if I have no savings they will debit me as normal?