Pathetic service

I have been a loyal customer for FNB for the past 17 years I'm trying to get a pre approval for a home loan but I'm told my application is referred due to my misconduct and credit behaviour. I have a perfect credit score so why they can not give me a simple pre approval. Other banks have pre approved me on a very low interest rate but I'm trying to be a loyal customer at FNB and I'm not getting service I deserve