Credit Rating Dispute!

I've been trying to apply for Vehicle finance for the past month, and for some odd reason, the banks have been declining and for the life of me, I did not understand as to why because I do not have a bad credit record. I have no debt, no outstanding amounts pending against my name. Well, so I thought... Yesterday I decided, enough is enough I am going to view my credit rating online and there it was. An outstanding amount from a Temp loan I took in December last year and paid in January 2015 was pending as outstanding against my name! I have raised a complaint to FNB but they do not find it necessary to get back to me, my own bank treating me like I'm irrelevant, but I will be raising a dispute, as this has tarnished my name for no reason but their lack of customer service. Giving them the benefit of the doubt, what a joke. Their customer care is clearly falling short a few kilometres, how can you ruin someone's life like this? As if it is not relevant? This is putrid! I am disappointed with this service, truly horrific.