Double Debiting

I am very disappointed by FNB way of doing things. Last December i took a small loan as part of building my credit score. Now in January FNB decides to triple debit me leaving me with no money and when I went to the branch all they could do was to tell me that they can see am debited wrongly and the only thing they can do is just to put me on the phone. I had spent hours being transferred from one person to another. I couldn't pay my rent due to this problem and no one is helping me. I regretting moving my salary to them and really I would have been much better with Capitec. Its really painful