St George Amplify Application - what's their criteria for approval?

Despite having a very good credit score and applying for a credit card with no minimum income requirement through a link on this website, I have been unsuccessful with the Bank for this application. Could not having an account with the St George Bank be a consideration and can they apply this as valid criteria? Is there anyway to make a complaint about the process?

I didn’t have any accounts with them and had no issue with my application. This is the first time i have had any dealings with st George.

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