Very bad service

So I have been using FNB for years and years, i was previously on debt review which has been paid up for over a year now, Now I've been trying to apply for a credit card with FNB because I bank with them but they keep on declining my applications with no reason as to why, I just need to build my credit score and FNB is not helping at all and worse this is the only bank I've been banking with for years and years,