Credit approval Nedbank

Got great service from nedbank regarding vehichle finance , desided to change all my banking to nedbank and close and pay off outstanding credit facilities. they immediately approved an overdraft facility, i then app**** for a credit card and they approved it immediately, but they amount approved was way to much i then cancelled the transaction and reapp**** for much less. now all of a sudden i am not credit worthy and don't qualify for nothing. HOW ON EARTH DO YOU GET THAT CULCULATION. SO DISAPPOINTED IF I KNEW I WOULD NEVER HAVE CHANGED ACCOUNTS.