Overdrafr Refusal

I just went to the FNB app to increase my overdraft facility. After capturing my info the application was kicked out stating that my credit record is low which is utter nonsense because if anything it has gone up as I have closed my loans and FNB credit for that matted? I am not sure what critieria they use to come to such decisions but I'm certainly not happy with their service thus far. I deserve better than this treatment, and its about time I explored my options. This is ridiculous!!!