With the new rules on credit cards that went into effect in February, Citi is absolutely correct to deny you credit here.

I assume that you are under 21? If you are under 21, then the bank must deny you credit unless you have the income to prove you can pay off the loans (and with open lines already equal to almost 50% of your stated income, this would be in doubt) unless you have a co-signer.

If you are over 21, the decision is still the same since your open lines to stated income is quite high. I would just let it go and wait until you graduate and begin earning a higher income.

Good for you that you have a high FICO and recognise the importance of maintaining your credit history. Consider this a minor bump in the road and get on with your life.