Credit score GOOD but FNB cannot grant Credit/ finance my car

i have been applying for vehicle finance at FNB but always declined, their reason was my credit score which was low. but recently my credit score is on green which is regarded as good but they are still declining, i even went to the branch to find out what could be the problem, they checked everything and the risk and they confirmed that my profile with FNB is very good but why are they declining when i am their client. what benefits am i getting from FNB? why must i stay with FNB when its treating me badly?