FNB extreme prejudice

I held an account at Standard Bank for almost 13 years but switched to FNB because of their claims to be better than everyone else. I had a debt with FNB which has now been paid up. I worked long and hard to repay that debt and clear my credit rating, paying a hefty amount of interest as well! After recently applying for a credit card with FNB I'm now told I must wait SIX MONTHS before they will consider me for credit. I think this is extremely unfair and prejudicial. I have a clear record and have never had any judgements against my name. What more am I supposed to do? Very unhappy and will most likely return to Standard Bank.