Due Diligence not done

I have now been a long standing customer for many years. I recently app**** for a credit limit increase on my account and sent through all documents etc. Woolworths credit card divisions incompetence shocked me as they did not do there due diligence whilst having a look at the bank statements. They did not taking all amounts in consideration. The increase was then declined but with my affordability and credit score this seemed abit off. I call to enquire the reason for the decline as this reflects bad with the credit bureau. Weeks have now past and still no answers. It's sad to see customers who pay there accounts well ,be treated like this. Even after numerous emails no one can tell me why or provide me with feedback. I am sadden by woolworths treatments of customers that support there businesses.