Interest rate charged is outside agreed terms

Standard Bank is *****ing from me. My student loan contract specifies a prime less 3 interest rate with a minimum of 7.5%, but they are currently charging me prime less 2%. <br> The amount might not be big, but if they are doing this to more people it definitely adds up!! AND... THIS IS *****ING!!<br> <br> Not only this, their \client center\" refuses and is unable to assist... they are rude (putting the phone down in my ear!!!!) and no one has a clue what's going on. I was passed from one extension to another for about an hour just to be told that I have to go into a branch to fix THEIR error!!<br> <br> I am sorry, but if this is Standard Bank's error, surely it should not have to inconvenience me!!?? Why should I have to spend god knows how long sitting in a branch, wasting my precious time and having to take off work to sort out YOUR mess Standard Bank???<br> <br> "