It's probably the high util% that's causing you a problem. That, plus your debt-to-income ratio might be bad if you have a bunch of balances to pay off on credit cards, plus an auto loan, plus a mortgage.
Not sure about the 'insufficient credit history' part, though. You should have a 2-3 year AAOA, so that would be one you could probably try to contest.
However, if your existing CCs are at 80% util already, you're probably going to have problems getting approved. After all, it looks to them, as a lender, that you're just grasping for more credit when your existing credit is already almost maxed out, so they'll be putting themselves in a higher risk of you defaulting if they approve you. So I'd say your best bet would be to work on getting your utilization down before you try to apply for any more credit.
