BAD CREDIT PROFILE FOR NO REASON.

I had loan with standard Bank between 2012 and 2013. I over paid the loan at Standard Bank and they had to refund me some of the money I've over paid on the loan. I app**** for a job went for the interview I couldn't get the job due to CREDIT PROFILE and when I called TRANSUNION to check for my ITC they told me that I owe Standard Bank R6685 from the loan. The gentleman from TRANSUNION advised me to go to Standard Bank and inquire about this, I went to Standard Bank today to rectify this and they told me everything is clear on my name I don't owe them anything but they've listed me at TRANSUNION as I'm owing them. They've told me that the only thing that they can help me with is a letter stating that I don't owe them anything. The letter which I will only receive next week Wednesday of which I need this sorted ASAP as this is affecting my career and delaying my goals and plans. I need my clear with TRANSUNION ASAP.